Be plentiful (6)
I believe the answer is:
abound
'be plentiful' is the definition.
(synonyms)
This is all the clue.
(Other definitions for abound that I've seen before include "On a bud (anag)" , "Be plentiful, be present on great quantities" , "Be prolific" , "Exist in large numbers" , "Exist plentifully" .)