Fish right out of ditch (5)
I believe the answer is:
tench
'fish' is the definition.
(tench is a kind of fish)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for tench that I've seen before include "catch" , "something fishy" , "Swimmer" , "One in school" , "Fish of the carp family" .)