Badly riled, he's not keen to work (5)
I believe the answer is:
'he's not keen to work' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'badly riled' is the wordplay.
'badly' is an anagram indicator.
'riled' is an anagram of 'IDLER'.
Can you help me to learn more?
(Other definitions for idler that I've seen before include "bad worker" , "Dodger" , "Lollard" , "One working to control tension" , "Not working so hard" .)