Ice-cream, cold one (4)
I believe the answer is:
cone
'ice-cream' is the definition.
(I've seen this in other clues)
'cold one' is the wordplay.
'cold' becomes 'c' (eg on taps).
'c'+'one'='CONE'
(Other definitions for cone that I've seen before include "Something dropped from tree" , "Road works marker" , "Tapering solid" , "99, maybe" , "Shape, the base is a circle and the sides taper up to a point" .)