Coffee-flavoured liqueur (3,5)
I believe the answer is:
'coffee-flavoured liqueur' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for tia maria that I've seen before include "Coffee-flavoured trademarked liqueur" , "Coffee-flavoured Caribbean liqueur" , "Rum-based coffee liqueur" , "drink is served?" , "After-dinner liqueur" .)