Abound, be plentiful (4)
I believe the answer is:
teem
This clue is a double definition.
'abound' is the first definition.
(I've seen this before)
'be plentiful' is the second definition.
(I've seen this in another clue)
(Other definitions for teem that I've seen before include "Bear" , "Come down hard" , "Seethe" , "(Of rain) pour down" , "Abound, swarm with" .)