Rich, that woman's relatives (7)
I believe the answer is:
fathers
'relatives' is the definition.
(father is a kind of relative)
'rich that woman's' is the wordplay.
'rich' becomes 'fat' ('fat' can be a synonym of 'rich').
'that woman' becomes 'hers' (I can't justify this - if you can you should give a lot more credence to this answer).
'fat'+'hers'='FATHERS'
Can you help me to learn more?
(Other definitions for fathers that I've seen before include "See 13" , "Sires" , "Takes ref's hat to the parents" .)