Playing for the team as a subsidiary (2,3,4)
I believe the answer is:
on the side
'as a subsidiary' is the definition.
I can't judge whether this definition defines the answer.
'playing for the team' is the wordplay.
'playing' becomes 'on' (on can mean playing or performing).
'for' says to put letters next to each other.
'team' becomes 'side' (both can mean a sports team).
'on'+'the'+'side'='ON THE SIDE'
Can you help me to learn more?
(Other definitions for on the side that I've seen before include "Without official authorisation" , "Selected for the team" , "Like illicit relationship" , "where one may have a bit?" , "in addition to one's usual occupation" .)