Overacting actor (3)
I believe the answer is:
ham
'overacting actor' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ham that I've seen before include "Meat; radio operator" , "under twenty-eight [HIP]" , "Bad actor; Noah son" , "Meat for the radio amateur" , "(Cooked or cured) thigh of pig" .)