Bad beer left for dissenter (5)
I believe the answer is:
rebel
'dissenter' is the definition.
(I know that rebel is a type of nonconformist)
'bad beer left' is the wordplay.
'bad' is an anagram indicator.
'left' becomes 'l' (common abbreviation).
'beer' anagrammed gives 'rebe'.
'rebe'+'l'='REBEL'
'for' is the link.
(Other definitions for rebel that I've seen before include "One refusing to conform" , "One who fights authority" , "Rise up against authority" , "Flouter of authority" , "One who rises up" .)