A smile’s turning haphazard (7)
I believe the answer is:
aimless
'haphazard' is the definition.
(I've seen this before)
'a smile's turning' is the wordplay.
'turning' indicates an anagram.
'smiles' is an anagram of 'imless'.
'a'+'imless'='AIMLESS'
(Other definitions for aimless that I've seen before include "not knowing where to go?" , "Melissa (anag) -- unmotivated" , "Without purpose or direction" , "Without direction or ambition" , "Lacking ambition or target" .)