Drink ruined a nice hat (5,3)
I believe the answer is:
china tea
'drink' is the definition.
(I've seen this before)
'ruined a nice hat' is the wordplay.
'ruined' indicates anagramming the letters.
'a'+'nice'+'hat'='anicehat'
'anicehat' anagrammed gives 'CHINA TEA'.
(Other definitions for china tea that I've seen before include "Leaves for drink" , "Eastern drink" , "cuppa?" .)