Bound to be penny amongst swept up leaves (8)
I believe the answer is:
strapped
'bound' is the definition.
(strapping is a kind of binding)
'penny amongst swept up leaves' is the wordplay.
'penny' becomes 'p' (short for pence).
'amongst' means one lot of letters goes inside another (I've seen this in other clues).
'swept up' says the letters should be written backwards (in a down clue, letters go up).
'leaves' becomes 'departs' (to leave is to depart a place).
'departs' in reverse letter order is 'straped'.
'p' going into 'straped' is 'STRAPPED'.
'to be' is the link.
(Other definitions for strapped that I've seen before include "- - for cash (hard up)" , "Without, or very short of, money" , "beaten" , "broke" , "not generating enough cash?" .)