Throw up a lot of grim seafood (7)
I believe the answer is:
lobster
'seafood' is the definition.
(lobster is a kind of seafood)
'throw up a lot of grim' is the wordplay.
'throw up' becomes 'lob' (I've seen this before**).
'a lot of' means to remove the last letter (most of the word but not all of it).
'grim' becomes 'stern' ('stern' can be a synonym of 'grim').
'stern' with its last letter taken away is 'ster'.
'lob'+'ster'='LOBSTER'
(Other definitions for lobster that I've seen before include "Crustacean with pincer-like claws" , "Bolster up te shellfish" , "Tommy no longer" , "Crustacean caught in pot" , "One showing claws" .)