Mollusc is cooked with Oban Ale (7)
I believe the answer is:
abalone
'mollusc' is the definition.
(abalone is a kind of mollusc)
'cooked with oban ale' is the wordplay.
'cooked' indicates anagramming the letters (letters cooked into a new form).
'with' says to put letters next to each other.
'oban' put next to 'ale' is 'obanale'.
'obanale' with letters rearranged gives 'ABALONE'.
'is' acts as a link.
(Other definitions for abalone that I've seen before include "Mollusc, the sea-ear" , "Ormer, ear shell" , "Source of mother-of-pearl" , "something to eat from the sea" , "Sea food must be found" .)