No starter for Ruth, one eating fish (5)
I believe the answer is:
egret
'fish' is the definition.
The definition and answer can be both animals as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for egret that I've seen before include "White wading bird" , "One of a pair of waders" , "Wading bird like a heron" , "white fish eater" , "Greet (anag) -- wading bird" .)