Cold joint and piece of fried potato (4)
I believe the answer is:
chip
'piece of fried potato' is the definition.
(I've seen this before)
'cold joint' is the wordplay.
'cold' becomes 'C' (eg on taps).
'joint' becomes 'hip' (part of body).
'c'+'hip'='CHIP'
'and' is the link.
(Other definitions for chip that I've seen before include "Sliver of wood or piece of potato" , "Small piece broken off something" , "Piece off block (or on shoulder?)" , "Murphy sliced" , "one bit of fast food > counter" .)