To give him credit could be stupid! (3)
I believe the answer is:
ass
This clue could be a double definition.
'to give him credit' is the first definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'stupid' is the second definition.
The answer and definition can be both people as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'could be' is the link.
Can you help me to learn more?
(Other definitions for ass that I've seen before include "Jennet" , "oaf" , "Quadruped; fool" , "Titania loved one" , "Hoofed animal, smaller than a horse" .)