Cash in my old points (5)
I believe the answer is:
money
'cash' is the definition.
(thesaurus)
'in my old points' is the wordplay.
'in' means one lot of letters goes inside another.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'points' becomes 'ne' (**).
'o'+'ne'='one'
'my' going around 'one' is 'MONEY'.
(Other definitions for money that I've seen before include "It's the root of all evil" , "Euro for example" , "Currency; wealth" , "Legal tender" , "'A fool and his.....are soon parted'" .)