Fish after small fruit (8)
I believe the answer is:
shaddock
'fruit' is the definition.
(shaddock is a kind of fruit)
'fish after small' is the wordplay.
'fish' becomes 'shad' (shad is a kind of fish).
'after small' becomes 'dock' (I can't explain this - if you can you should believe this answer much more).
'shad'+'dock'='SHADDOCK'
Can you help me to learn more?
(Other definitions for shaddock that I've seen before include "Tropical fruit" , "Pomelo" , "Citrus fruit" , "tree" .)