This ham's potentially a huge success (5,3)
I believe the answer is:
smash hit
'a huge success' is the definition.
(a smash hit is something very successful)
'this ham's potentially' is the wordplay.
'potentially' indicates anagramming the letters (letters have the potential to spell a new word).
'this'+'hams'='thishams'
'thishams' with letters rearranged gives 'SMASH-HIT'.
(Other definitions for smash hit that I've seen before include "successful play?" , "Huge success" , "most popular show!" , "great entertainment" , "roaring success" .)