Sea life caught by the mouth (5)
I believe the answer is:
coral
'sea life' is the definition.
The definition and answer can be both animals as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'caught by the mouth' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'by' says to put letters next to each other.
'the mouth' becomes 'oral' (I can't justify this - if you can you should give a lot more credence to this answer).
'c'+'oral'='CORAL'
Can you help me to learn more?
(Other definitions for coral that I've seen before include "Marine growth" , "Reef-forming skeletons" , "Main resident" , "Tiny animal forming reef" , "Pink - lobster roe" .)