Not hearing about cold drink (5)
I believe the answer is:
decaf
'drink' is the definition.
(I've seen this before)
'not hearing about cold' is the wordplay.
'not hearing' becomes 'deaf' ('deaf' is the opposite to 'hearing').
'about' means one lot of letters goes inside another.
'cold' becomes 'c' (eg on taps).
'deaf' placed around 'c' is 'DECAF'.
(Other definitions for decaf that I've seen before include "Coffee without the kick?" , "Less stimulating coffee?" , "Type of coffee" , "Cup substitute missing kick" , "Non-alcoholic drink" .)