Treated smile as random (7)
I believe the answer is:
aimless
'random' is the definition.
(I've seen this in another clue)
'treated smile as' is the wordplay.
'treated' is an anagram indicator.
'smile'+'as'='smileas'
'smileas' anagrammed gives 'AIMLESS'.
(Other definitions for aimless that I've seen before include "Without purpose or plan" , "Without direction or ambition" , "Drifting - Melissa (anag)" , "Lacking ambition or target" , "Like characters in 5D {WAITING FOR GODOT]" .)