Face drop during struggle (6)
I believe the answer is:
visage
'face' is the definition.
(visage is a kind of face)
'drop during struggle' is the wordplay.
'drop' becomes 'sag' (sagging is a kind of dropping).
'during' is an insertion indicator.
'struggle' becomes 'vie' (I've seen this before).
'sag' placed inside 'vie' is 'VISAGE'.
(Other definitions for visage that I've seen before include "Mug" , "Face, aspect" , "Clock" , "A person's face, countenance" .)