Decent swapping parts for someone else (3,3)
I believe the answer is:
per pro
'decent swapping parts' is the definition.
I can't judge whether this definition defines the answer.
'someone else' is the wordplay.
I cannot quite see how this works, but
'someone' could be 'pro' (pro is a kind of someone) and 'pro' is present in the answer.
The remaining letters 'per' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'for' is the link.
Can you help me to learn more?
(Other definitions for per pro that I've seen before include "How one signs for another" , "'pp' (signature) in full" , "By proxy" , "Abbreviation used signing a letter for another" .)