Two pieces for minor role (3,4)
I believe the answer is:
bit part
'minor role' is the definition.
(synonyms)
'two pieces' is the wordplay.
'two pieces' means two replacements for 'piece'.
'piece' becomes 'bit' (synonyms).
'piece' becomes 'part' (synonyms).
'bit'+'part'='BIT PART'
'for' is the link.
(Other definitions for bit part that I've seen before include "Very minor role" , "'Small role in film or play (3,4)'" , "Tool" , "Small acting role" , "cameo" .)