As an actor, a very good sandwich-man (3)
I believe the answer is:
ham
'man' is the definition.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for ham that I've seen before include "This actor overacts" , "one rescued from flood" , "One of Noah's sons" , "(Cooked or cured) thigh of pig" , "Succulent meat or extravagant actor" .)