Unaware about cold drink (5)
I believe the answer is:
decaf
'drink' is the definition.
(decaffeinated coffee)
'unaware about cold' is the wordplay.
'unaware' becomes 'deaf' (I can't justify this - if you can you should give a lot more credence to this answer).
'about' indicates putting letters inside.
'cold' becomes 'C' (eg on taps).
'deaf' placed around 'c' is 'DECAF'.
Can you help me to learn more?
(Other definitions for decaf that I've seen before include "Non-alcoholic drink" , "Coffee without the kick?" , "Cup substitute missing kick" , "Style of coffee" , "Type of coffee" .)