After correction, smile, as lacking purpose (7)
I believe the answer is:
aimless
'lacking purpose' is the definition.
(I've seen this before)
'after correction smile as' is the wordplay.
'after correction' indicates anagramming the letters (I've seen this in other clues).
'smile'+'as'='smileas'
'smileas' is an anagram of 'AIMLESS'.
(Other definitions for aimless that I've seen before include "Drifting - Melissa (anag)" , "Like characters in 5D {WAITING FOR GODOT]" , "Lacking ambition or target" , "Melissa (anag) -- unmotivated" , "Haphazard" .)