Sent round small amount of money as a deposit (8)
I believe the answer is:
sediment
'a deposit' is the definition.
(I know that deposit can be written as sediment)
'sent round small amount of money' is the wordplay.
'round' is an insertion indicator.
'small amount of money' becomes 'dime' (I am not sure about this - if you are sure you should believe this answer much more).
'sent' placed around 'dime' is 'SEDIMENT'.
'as' is the link.
Can you help me to learn more?
(Other definitions for sediment that I've seen before include "Grounds - debris" , "Particles that settle on the bottom of river or wine" , "Send item (anag)" , "Remains" , "Dregs; deposit" .)