New store has variable seafood (6)
I believe the answer is:
oyster
'seafood' is the definition.
(oyster is a type of seafood)
'new store has variable' is the wordplay.
'new' indicates an anagram.
'has' is an insertion indicator.
'variable' becomes 'y' (algebra).
'store' is an anagram of 'oster'.
'oster' placed around 'y' is 'OYSTER'.
(Other definitions for oyster that I've seen before include "Pearl-producing bivalve" , "Mollusc with shucks" , "aphrodisiac?" , "Seafood item sometimes eaten alive" , "Pearl's home?" .)