Underwater ink squirter (5)
I believe the answer is:
squid
'underwater ink squirter' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for squid that I've seen before include "Catch" , "Cephalopod mollusc" , "Edible eight-arm mollusc" , "Large cephalopod" , "Calamari" .)