Ice cream makes it a cold one (4)
I believe the answer is:
cone
'ice cream' is the definition.
(cone can refer to an ice cream cone)
'cold one' is the wordplay.
'cold' becomes 'C' (eg on taps).
'c'+'one'='CONE'
'makes it a' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for cone that I've seen before include "Something dropped from tree" , "Road furniture!" , "Hollow object associated with ice cream and motorways" , "standing in middle of motorway" , "children can lick" .)