The case of the circus performers and the old slattern (7)
I believe the answer is:
fleabag
'the old slattern' is the definition.
The definition suggests a singular noun which matches the answer.
'the case of the circus performers' is the wordplay.
I cannot quite understand how this works, but
'case' could be 'bag' (bag is a kind of case) and 'bag' is found in the answer.
The remaining letters 'flea' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'and' acts as a link.
Can you help me to learn more?
(Other definitions for fleabag that I've seen before include "Scruffy animal" , "run-down hotel" , "Scruffy person; seedy hotel (US)" , "Dirty person or animal" .)