Joy's keeping diamonds and money available (5)
I believe the answer is:
funds
'money available' is the definition.
I can't judge whether this definition defines the answer.
'joy's keeping diamonds' is the wordplay.
'joy' becomes 'funs' (I can't justify this - if you can you should believe this answer much more).
'keeping' is an insertion indicator (some letters kept inside).
'diamonds' becomes 'd' (abbreviation for the card suit diamonds).
'funs' enclosing 'd' is 'FUNDS'.
'and' is the link.
Can you help me to learn more?
(Other definitions for funds that I've seen before include "Finances" , "Liquid assets" , "Available cash" .)