Tilapia is freshest spit cooked (2,6,4)
I believe the answer is:
st peters fish
Here is my best explanation:
'tilapia' is the definition.
(type of fish nicknamed St Peter's fish)
'freshest spit cooked' is the subsidiary indication.
'cooked' indicates an anagram.
'freshestspit' anagrammed gives 'stpetersfish'.
'is' is the link.
(Another definition for st peters fish that I've seen is "Edible fish of Middle East".)