Will he not still be humorous? (3)
I believe the answer is:
wag
'will he not still be humorous?' 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 wag that I've seen before include "Move briskly from side to side like tail" , "Shake" , "Comedian" , "card" , "The wit to move the tail" .)