Is he trying to fool you by being more hearty? (7)
I believe the answer is:
bluffer
'is he trying to fool you by being more hearty?' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
This is all the clue.
Can you help me to learn more?
(Other definitions for bluffer that I've seen before include "More frank" , "is he trying to take you in?" , "Deceiver" , "One trying to deceive" .)