Graduate runs into French port, mostly for squid (8)
I believe the answer is:
'squid' is the definition.
('calamari' can be a synonym of 'squid')
'graduate runs into french port mostly' is the wordplay.
'graduate' becomes 'ma' (abbreviation for Master of Arts).
'runs' becomes 'r' (cricket abbreviation).
'into' means one lot of letters goes inside another.
'french port' becomes 'calais' (I've seen this before).
'mostly' means to remove the last letter.
'calais' with its final letter taken away is 'calai'.
'mar' put into 'calai' is 'CALAMARI'.
'for' acts as a link.
(Other definitions for calamari that I've seen before include "Squid prepared as food", "Squid served as food", "Mollusc", "seafood", "Battered squid rings".)