Lie back with fine punch (4)
I believe the answer is:
biff
'punch' is the definition.
('biff' can be a synonym of 'punch')
'lie back with fine' is the wordplay.
'lie' becomes 'fib' (fib is a kind of lie**).
'back' says the letters should be written backwards.
'with' means one lot of letters go next to another.
'fine' becomes 'f' (abbreviation).
'fib' in reverse letter order is 'bif'.
'bif'+'f'='BIFF'
(Other definitions for biff that I've seen before include "Punch" , "Hard blow with fist" , "strike" .)