General form of increase (7)
I believe the answer is:
enlarge
'increase' is the definition.
(I know that enlarge is a more specific form of increase)
'general form' is the wordplay.
'form' indicates anagramming the letters (a different form of the same letters).
'general' anagrammed gives 'ENLARGE'.
'of' is the link.
(Other definitions for enlarge that I've seen before include "Expatiate" , "Stretch" , "Gleaner (anag.)" , "Grow" , "Make bigger in general" .)