Security for a loan (10)
I believe the answer is:
collateral
'security for a loan' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for collateral that I've seen before include "Money put up" , "Security for loan repayment; secondary" , "Confirmatory - recall a lot (anag)" , "subsidiary" , "running side by side" .)