A hardier drunk keeps going with it (8)
I believe the answer is:
diarrhea
'a hardier drunk keeps going with it' is the definition.
I can't judge whether this defines the answer.
'a hardier drunk keeps' is the wordplay.
'drunk' is an anagram indicator.
'keeps' is an insertion indicator (inserted letters are kept inside).
'hardier' is an anagram of 'dirrhea'.
'a' inserted into 'dirrhea' is 'DIARRHEA'.
Can you help me to learn more?
(Another definition for diarrhea that I've seen is " runs in Kentucky".)