Winger losing front part of foot (4)
I believe the answer is:
inch
'part of foot' is the definition.
(12 inches in a foot)
'winger losing front' is the wordplay.
'winger' becomes 'finch' (finch is a kind of bird).
'losing front' means to remove the first letter.
'finch' with its initial letter taken off is 'INCH'.
(Other definitions for inch that I've seen before include "Two point five four cm" , "See 12" , "Edge slowly" , "Move slowly, in small steps" , "Measure of length" .)