Bigger, greater (6)
I believe the answer is:
larger
I believe this clue is a double definition.
'bigger' is the first definition.
('large' can be a synonym of 'big')
'greater' is the second definition.
('large' can be similar in meaning to 'great')
(Other definitions for larger that I've seen before include "Bigger, greater" , "Comparatively bigger" , "Greater in size" , "Ebullient person may be describes as ?? than life" , "more stout" .)