Jazz fan bored by plain acts at club (7)
I believe the answer is:
cabaret
'club' is the definition.
(I've seen this before)
'jazz fan bored by plain' is the wordplay.
'jazz fan' becomes 'cat' (slang term for a jazz fan).
'bored by' means one lot of letters goes inside another (to bore something can mean to drill into it).
'plain' becomes 'bare' (similar in meaning).
'cat' enclosing 'bare' is 'CABARET'.
'acts at' acts as a link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for cabaret that I've seen before include "Bob Fosse musical with Liza Minnelli" , "Revue" , "Floor show for Arab etc" , "Floor-show as in nightclub" , "Film set in 1931 Berlin - floor show" .)