Slip outside from fire after smoke retreats (5)
I believe the answer is:
gaffe
'slip' is the definition.
(both can mean an error or blunder)
'outside from fire after smoke retreats' is the wordplay.
'outside from' means to remove the middle letters (the outside letters of the word).
'after' is a charade indicator (letters next to each other).
'smoke' becomes 'fag' (both can mean a cigarette).
'retreats' says the letters should be written backwards (I've seen 'retreating' mean this).
'fire' with its centre taken out is 'fe'.
'fag' written backwards gives 'gaf'.
'fe' after 'gaf' is 'GAFFE'.
(Other definitions for gaffe that I've seen before include "Brick (that's dropped)" , "embarrassing mistake" , "Remark one wishes unmade" , "embarrassing error" , "slip" .)