Mugs, fine ones (5)
I believe the answer is:
faces
'mugs' is the definition.
(mug can informally mean one's face)
'fine ones' is the wordplay.
'fine' becomes 'f' (abbreviation).
'ones' becomes 'aces' ('ace' can be a synonym of 'one').
'f'+'aces'='FACES'
(Other definitions for faces that I've seen before include "Confronts" , "Meets defiantly - moves head accordingly" , "With 1a [NEW], TV talent show" , "Mugs" .)