He may deceive or upset some of the guests (5)
I believe the answer is:
rogue
'he may deceive or upset some of the guests' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he' is the wordplay.
I cannot really understand how this works, but
'he' could be 'rog' and 'rog' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for rogue that I've seen before include "Wild animal driven away from herd" , "One dishonest" , "Rascal or reprobate" , "Charlatan" , "Blackguard" .)