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