Pile of money, money, money — small amount dropped off (5)
I believe the answer is:
mound
'pile' is the definition.
(synonyms)
'of money money money small amount dropped off' is the wordplay.
'of money' becomes 'm' (I can't justify this - if you can you should give a lot more credence to this answer).
'money' becomes 'pound' (I've seen this in other clues).
'money small amount' becomes 'p' (short for pence, a small amount of money).
'dropped off' indicates named letters should be taken away.
'pound' with 'p' taken away is 'ound'.
'm'+'ound'='MOUND'
(Other definitions for mound that I've seen before include "Heap (of raised earth)" , "Raised mass of earth" , "Earth bank" , "Heap, hillock" , "Hillock; gold ball (Her.)" .)