Demanding fish stew for starters (9)
I believe the answer is:
gruelling
'demanding' is the definition.
(I've seen this before)
'fish stew for starters' is the wordplay.
I cannot really see how this works, but
'fish' could be 'ling' (ling is a kind of fish) and 'ling' is present in the answer.
The remaining letters 'gruel' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for gruelling that I've seen before include "Severe" , "Demanding" , "Arduous, backbreaking" , "Strenuous" .)