Music a man has to work at (5)
I believe the answer is:
rondo
'music' is the definition.
(rondo is a kind of music)
'a man has to work at' is the wordplay.
I cannot really see how this works, but
'man' could be 'ron' (man's name) and 'ron' is found within the answer.
'work' could be 'do' (synonyms) and 'do' is located in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for rondo that I've seen before include "Repetitive musical form" , "noted work" , "part of a sonata" , "Musical piece with a recurring theme" , "Music form with recurring theme" .)