Across
Brief advice (7)
Figure in plane has spell with no end of bad pain (7)
It’s often attached to a post or similar (4)
In this state one is making a new life (9)
Obvious feature of Middle America (5)
Tried to restore computer, and gave it another kick? (8)
Very angry playwright’s heard (4)
I haven't cracked this one yet — but Fifteensquared have:
Soinds like (‘heard’) WILDE (Oscar, ‘playwright’).
Destroy some trees, a real setback (5)
Face relaxed? (4)
I haven't cracked this one yet — but Fifteensquared have:
DIAL is LAID BACK (‘relaxed’).
Open water is hateful: I may get left on the beach (8)
I haven't cracked this one yet — but Fifteensquared have:
A charade of SEA’S (‘open water is’) plus HELL (‘hateful’).
In Colorado, had encounter with visitor from space (5)
Only Plan A flies for unquenchable optimist (9)
John, who composed four notes (4)
I haven't cracked this one yet — but Fifteensquared have:
C A G E (‘four notes’).
Torment with base wickedness (7)
Comprehensive classes, back to school (7)
I haven't cracked this one yet — but Fifteensquared have:
A charade of GENERA (‘classes’; in taxonomy the two are quite distinct) plus L (‘back to schoo L ‘).
Down
Go off one Caribbean snack (4)
I haven't cracked this one yet — but Fifteensquared have:
A charade of ROT (‘go off’) plus I (‘one’).
One short order available when requested (2,6)
I haven't cracked this one yet — but Fifteensquared have:
A charade of ‘on[e]’ minus its last letter (‘short’) plus DEMAND (‘order’).
I’m so obsequious, men say nastily (3-3)
To live on farmland can be endured (8)
A better place (6)
Modest, keeping son comfortable (4)
I haven't cracked this one yet — but Fifteensquared have:
An envelope (‘keeping’) of S (‘son’) in COY (‘modest’).
Waterproof sheet colleague and I dropped into lake (9)
I haven't cracked this one yet — but Fifteensquared have:
An envelope (‘dropped into’) of PAUL (‘colleague’, fellow Guardian crossword setter) plus ‘I’ in TARN (‘lake’).
Group of cats, one among several that are deadly (5)
I haven't cracked this one yet — but Fifteensquared have:
PRIDE being one of the seven deadly sins.
Insist upon intercourse, but soprano refused (5)
The whole lot in English, with remarkable brevity (5,3)
I haven't cracked this one yet — but Fifteensquared have:
A charde of E (‘English’) plus VERYBIT, an anagram (‘remarkable’ – one of the less justifiable anagrinds) of ‘brevity’.
Legendary swordsman does calm exercises (8)
One applying ointment from tray (6)
Haul into court to obtain small dwelling (6)
Expose the flesh of Prime Minister (4)
Keep chewing and not speaking (4)
Type letters or click words in the clue