Workman excited over pieta (9)
I believe the answer is:
'workman' is the definition.
'excited over pieta' is the wordplay.
'excited' is an anagram indicator.
'overpieta' with letters rearranged gives 'OPERATIVE'.
(Other definitions for operative that I've seen before include "Machinist - working", "Significant", "American detective", "Efficient", "Worker in manufacturing".)