Another RJ with some tricky words. I wasn't particularly jazzed with some of the clues. 20D and 26A were particularly weird parses. The definition mechanism for 28A felt a bit unfair. Never heard of 13A, 21A, 26A or BRAW as part of 1D. Anyway, we got there...
Across
- 1
- Quickly rung bashers Kelly and Hall (11)
BUSHRANGERS — anagram (quickly) of RUNG BASHERS - 7
- Bird returned without ring in the morning (3)
MOA — reversal (returned) of O (ring) inside AM (in the morning) - 9
- Quantities go up in Asia (7)
AMOUNTS — MOUNT (go up) in AS (Asia) - 10
- Crew member to look for a dandy (7)
COXCOMB — COX (crew member) COMB (to look for) - 11
- Marks bills (5)
NOTES — double def. - 12
- Weakening independent politician giving expression (9)
IMPAIRING — I (independent) MP (politician) AIRING (giving expression) - 13
- John Lander, executive? (4,5)
HEAD BUYER — HEAD (John) BUYER (lander) - 16
- Chat about order for a rev-counter (5)
TACHO — anagram (about) of CHAT, O (order) - 18
- Floridly depend with diamonds involved (5)
REDLY — RELY (depend) with D (diamonds) inside - 19
- Caught by Kent's Lane, rest unhappily in confines (9)
CLOISTERS — C (caught) LOIS (Kent's Lane), anagram (unhappily) of REST - 21
- A bird lulling each crook (9)
GALLINULE — anagram (crook) of LULLING EA (each) - 23
- Do better than media boss in a cloak (5)
CAPED — CAP (do better than) ED (media boss) - 25
- Selected five commercials about last chance attacks (7)
INVADES — IN (selected) V (five) ADS (commercials) with E (last letter of chance) inside - 26
- Was she at the grog shop? (7)
SHEBEEN — SHE, BEEN (was), cryptic def. - 27
- Wander about in the evening. A dark one (3)
GAD — hidden in eveninG A Dark - 28
- News, say we blessed it madly (11)
WILDEBEESTS — anagram (madly) of WE BLESSED IT
Down
- 1
- Fine point to pickled pig's head (5)
BRAWN — BRAW (fine) N (point) - 2
- Shy worker gets script (9)
SHORTHAND — SHORT (shy) HAND (worker) - 3
- Bookies hoops? (5)
RINGS — double def. - 4
- In a threatening manner, never around, not quite still (7)
NASTILY — NAY (never) around STIL (still without last letter) - 5
- Fugitive has hesitation about South Head (7)
ESCAPER — ER (hesitation) around S (south) CAPE (head) - 6
- Seconds are hit and set out following boundary (9)
SIXTIETHS — anagram (out) of HIT SET after SIX (boundary) - 7
- Wander up to the writer, a New Zealander (5)
MAORI — reversal (up) of ROAM (wander), I (the writer) - 8
- You, say, bigamous - unlikely, doubtful (9)
AMBIGUOUS — angaram (unlikely) of U (homophone of you) BIGAMOUS - 13
- Difficult conditions causing U.S. president to move inside (4,5)
HARD GOING — HARDING (US president) with GO (to move) inside - 14
- An opening for a horse with a computer feature (3,6)
BAY WINDOW — BAY (a horse) WINDOW (a computer feature) - 15
- Well, not initially in small measure (3)
ELL — wELL without first letter - 17
- Poor quality of cold old car on headland (9)
CHEAPNESS — C (cold) HEAP (old car) NESS (headland) - 19
- Advocate ounces conversion to pound (7)
COUNSEL — anagram (conversion) of OUNCES, L (pound) - 20
- Look after it's finished - right! (7)
OVERSEE — SEE (look) after OVER (finished), &lit - 22
- Taken around avenue and bathed (5)
LAVED — LED (taken) around AV (avenue) - 23
- Dismissing from discrete island? (5)
CRETE — disCRETE without dis (missing) - 24
- Drops in and demands payment. About a thousand (5)
DUNKS — DUNS (demands payment) around K (a thousand)