Deal with fine crack (4)
I believe the answer is:
face
'deal with' is the definition.
(I've seen this before)
'fine crack' is the wordplay.
'fine' becomes 'f' (abbreviation).
'crack' becomes 'ace' (I've seen this before).
'f'+'ace'='FACE'
(Other definitions for face that I've seen before include "TV show" , "Front -- confront" , "Cope with" , "Outward appearance" , "steep side of mountain" .)