Jazzman Benny: nice chap? (7)
I believe the answer is:
goodman
'jazzman benny' is the definition.
'goodman' can be an answer for 'benny' (musician Benny Goodman is an example). I'm not sure about the 'jazzman' bit.
'nice chap?' is the wordplay.
'nice' becomes 'good' (similar in meaning).
'chap?' becomes 'man' (chap can mean a man).
'good'+'man'='GOODMAN'
Can you help me to learn more?
(Other definitions for goodman that I've seen before include "jazz player" , "Benny ___ , 'King of Swing'" , "Jazz musician" .)