With little support millions fall in floods (4)
I believe the answer is:
teem
'fall in floods' is the definition.
The definition and answer can be both to do with fundamental existence as well as being verbs in their base form.
Maybe you can see a link between them that I don't see?
'with little support millions' is the wordplay.
'with' means one lot of letters go next to another.
'little support' becomes 'tee'.
'millions' becomes 'm' (abbreviation).
'tee' next to 'm' is 'TEEM'.
Can you help me to learn more?
(Other definitions for teem that I've seen before include "Flow copiously" , "Abound - pour" , "Be prolific" , "Move in large numbers" , "Bucket down" .)