The fish do get caught rising (3)
I believe the answer is:
cod
'the fish' is the definition.
(type of fish)
'do get caught rising' is the wordplay.
'get' says to put letters next to each other.
'caught' becomes 'c' (cricket abbreviation).
'rising' says the letters should be written backwards (going up in a down clue).
'do'+'c'='doc'
'doc' written backwards gives 'COD'.
(Other definitions for cod that I've seen before include "Cash on delivery, in short, for this fish" , "to be paid for when it arrives" , "catch!" , "One caught in the deep maybe" , "No payment in advance" .)