Profit on salad and chips to support one of the parties (4,5)
I believe the answer is:
take sides
'profit on salad and chips to support one' is the definition.
I can't tell whether this definition defines the answer.
'of the parties' is the wordplay.
'of' becomes 'take' (I am not sure about this - if you are sure you should believe this answer much more).
'the parties' becomes 'sides' (I've seen this before).
'take'+'sides'='TAKE SIDES'
Can you help me to learn more?
(Other definitions for take sides that I've seen before include "Prefer a party" , "Support one faction" , "choose who to support" , "Join the struggle" , "Support one group over another" .)