It's a bit of a shame he can't act (3)
I believe the answer is:
ham
'it's a bit of a shame he can't act' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'it's a bit of a shame he' is the wordplay.
'it's a bit of' says the answer is hidden in the clue.
'HAM' is hidden within 'shame he'.
Can you help me to learn more?
(Other definitions for ham that I've seen before include "Cured pig's meat" , "One of Noah's sons" , "Meat served in sandwiches" , "Tasty meat for thespian who overacts" , "A poor actor - overdoes it" .)