Endless fish brought up, caught with this? (3)
I believe the answer is:
rod
'caught with this?' is the definition.
(fish may be caught with a fishing rod)
'endless fish brought up' is the wordplay.
'endless' means to remove the last letter.
'fish' becomes 'dory' (dory is a kind of fish).
'brought up' says the letters should be written in reverse (in a down clue, letters go up).
'dory' with its final letter removed is 'dor'.
'dor' reversed gives 'ROD'.
(Other definitions for rod that I've seen before include "pistol" , "The fly fisherman's stick" , "Flexible stick for 11 Down" , "See 13" , "Angler's equipment" .)