Exposed cards used without us being generous (4-6)
I believe the answer is:
open-handed
'generous' is the definition.
(I've seen this before)
'exposed cards used without us' is the subsidiary indication.
'exposed' becomes 'open' ('open' can be a synonym of 'exposed'**).
'cards' becomes 'hand' (I've seen this in other clues).
'without' suggests deleting specific letters.
'used' with 'us' taken away is 'ed'.
'open'+'hand'+'ed'='openhanded'
'being' is the link.
(Other definitions for open-handed that I've seen before include "Generous" , "Big-hearted?" .)