Seconds served with fish and pomelo (8)
I believe the answer is:
shaddock
'pomelo' is the definition.
(synonyms)
'seconds served with fish' is the wordplay.
I cannot quite understand how this works, but
'seconds' could be 's' (abbreviation) and 's' is found in the answer.
'fish' could be 'haddock' (haddock is a kind of fish) and 'haddock' is present in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'and' is the link.
Can you help me to learn more?
(Other definitions for shaddock that I've seen before include "Citrus fruit" , "Pomelo" , "Tropical fruit" , "tree" .)