Exists in large quantities (7)
I believe the answer is:
abounds
'exists in large quantities' is the definition.
('abound' can be a synonym of 'exist in large quantities')
This is all the clue.
(Other definitions for abounds that I've seen before include "Exists in large numbers or amounts" , "Is plentiful" , "Is all over the place" , "Flourishes" , "Exists in large quantities" .)