Have no credit in old money (3)
I believe the answer is:
own
'have' is the definition.
(to have something is to own it)
'no credit in old money' is the wordplay.
'no' becomes 'O' (resembles 0 - 'no' can mean 'zero').
'credit in old money' becomes 'wn' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'o'+'wn'='OWN'
(Other definitions for own that I've seen before include "Acknowledge" , "Control" , "Have in one's possession" , "Possess or confess" , "Personal; possess" .)