Take precedence in favour of self (6)
I believe the answer is:
forego
'take precedence' is the definition.
(I've seen this before)
'in favour of self' is the wordplay.
'in favour of' becomes 'for' (being for a particular cause).
'self' becomes 'ego' (synonyms).
'for'+'ego'='FOREGO'
(Other definitions for forego that I've seen before include "Take precedence" , "Get ahead" , "Go without, give up" , "Precede (in place/time)" , "Manage without" .)