She's said to be a moaner (4)
I believe the answer is:
mona
'she's' is the definition.
'said to be a moaner' is the wordplay.
I cannot really understand how this works, but
'a' is within the answer.
The remaining letters 'mon' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for mona that I've seen before include "Lisa in the Louvre" , "Female" .)