The cash I had as cover (3)
I believe the answer is:
lid
'cover' is the definition.
(lid is a kind of cover)
'the cash i had' is the wordplay.
'the cash' becomes 'l' (The pound sterling symbol is an elaborate L).
'i had' becomes 'id' (I'd).
'l'+'id'='LID'
'as' acts as a link.
(Other definitions for lid that I've seen before include "Removable cover of a container" , "Cover from gliders" , "Hinged or removable cover as for bottle" , "Cap or top for container" , "Hat" .)