Faint, having lost capital, using extremely deficient breed for race held here (7)
I believe the answer is:
aintree
'extremely deficient breed for race held here' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'faint having lost capital' is the wordplay.
I cannot really see how this works, but
'capital' could be 'ai' (resembles 'A1', old-fashioned term for excellent) and 'ai' is located in the answer.
This explanation may well be incorrect...
'using' is the link.
Can you help me to learn more?
(Other definitions for aintree that I've seen before include "Trainee in Grand National venue" , "Here they run" , "Home of the Grand National" , "Liverpool's racecourse" , "National racecourse" .)