Did he associate fishily with Ethel? (6)
I believe the answer is:
merman
'did he associate fishily with ethel?' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'did he' is the wordplay.
I cannot really understand how this works, but
'he' could be 'man' (I've seen this in another clue) and 'man' is found within the answer.
The remaining letters 'mer' 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 merman that I've seen before include "Ethel --, singer" , "fishy character" , "Fabulous creature" , "Half man, half fish" .)