Ice cream producing cold digit (4)
I believe the answer is:
cone
'ice cream' is the definition.
(cone can refer to an ice cream cone)
'cold digit' is the wordplay.
'cold' becomes 'c' (eg on taps).
'digit' becomes 'one' (one is a kind of digit).
'c'+'one'='CONE'
'producing' is the link.
(Other definitions for cone that I've seen before include "Hollow object associated with ice cream and motorways" , "It produces the seed for the pine tree" , "Motorway menace" , "Road works marker" , "Circular pyramid" .)