General form of increase (7)
I believe the answer is:
enlarge
'increase' is the definition.
(enlarging is a kind of increasing)
'general form' is the wordplay.
'form' indicates an anagram.
'general' is an anagram of 'ENLARGE'.
'of' is the link.
(Other definitions for enlarge that I've seen before include "Expatiate" , "Stretch" , "Gleaner (anag.)" , "Grow" , "Make bigger in general" .)