Hand is covered by foot (4)
I believe the answer is:
fist
'hand' is the definition.
(hand curled into a fist)
'is covered by foot' is the wordplay.
'covered by' is an insertion indicator.
'foot' becomes 'ft' (synonyms).
'is' inserted into 'ft' is 'FIST'.
(Other definitions for fist that I've seen before include "Balled hand" , "handwriting?" , "Punch dispenser" , "or be decked in a ring" , "duke" .)