Particular sort of female American dog, perhaps (7)
I believe the answer is:
fusspot
'particular sort' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'female american dog perhaps' is the wordplay.
'female' becomes 'f' (abbreviation).
'american' becomes 'US' (abbreviation for United States).
'dog perhaps' becomes 'spot' (I can't justify this - if you can you should give a lot more credence to this answer).
'f'+'us'+'spot'='FUSSPOT'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for fusspot that I've seen before include "I worry" , "Pernickety person" , "Person hard to please" , "Old woman" , "Over-fastidious person" .)