Player who's perhaps switched sides gets negotiator (10)
I believe the answer is:
transactor
'negotiator' is the definition.
(I have seen 'A negotiator' mean 'transactor' so perhaps 'negotiator' could also mean 'transactor')
'player who's perhaps switched sides' is the wordplay.
I cannot quite understand how this works, but
'player' could be 'actor' (synonyms) and 'actor' is located in the answer.
This explanation may well be incorrect...
'gets' acts as a link.
(Other definitions for transactor that I've seen before include "A negotiator" , "Businessman" .)