He quibbles about suits after the bill goes up (7)
I believe the answer is:
casuist
'he quibbles' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'about suits after the bill goes up' is the wordplay.
'about' is an anagram indicator.
'after' means one lot of letters go next to another.
'the bill' becomes 'ac' (short for account).
'goes up' is a reversal indicator.
'ac' back-to-front is 'ca'.
'suits' anagrammed gives 'suist'.
'suist' after 'ca' is 'CASUIST'.
Can you help me to learn more?
(Other definitions for casuist that I've seen before include "fine debater" , "Theological hair-splitter" , "One quibbles" , "He uses clever but false reasoning on moral issues" .)