His performance may set people reeling (5)
I believe the answer is:
piper
'his performance may set people reeling' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
This is the entire clue.
Can you help me to learn more?
(Other definitions for piper that I've seen before include "One plays" , "English painter and stained glass designer, d. 1992" , "If you pay him, call the tune" , "Scots musician" , "Highland instrumentalist" .)