Cup of tea left to chill (7)
I believe the answer is:
chalice
'cup' is the definition.
(chalice is a kind of cup)
'tea left to chill' is the wordplay.
'tea' becomes 'cha' (cha is a type of tea).
'left' becomes 'l' (common abbreviation).
'to chill' becomes 'ice' (icing is a kind of chilling).
'cha'+'l'+'ice'='CHALICE'
'of' is the link.
(Other definitions for chalice that I've seen before include "Church vessel" , "Eucharistic cup" , "Cup used in church" , "Necessity for communion" , "bowl" .)