In favour of (3)
'in favour of' is the definition.
(being for a particular cause)
This is the entire clue.
(Other definitions for for that I've seen before include "In support of" , "On the side of" , "Approving" , "Pro" , "See 24" .)
'in favour of' is the definition.
(being pro a particular cause)
This is the entire clue.
(Other definitions for pro that I've seen before include "Expert (abbr)" , "For; non-amateur" , "In short, not an amateur" , "Competent person" , "Paid worker" .)