Bird or Turkey stuffing - go large (6)
I believe the answer is:
petrel
'bird' is the definition.
(petrel is a kind of bird)
'turkey stuffing go large' is the wordplay.
'turkey' becomes 'tr' (abbreviation eg in internet addresses).
'stuffing' means one lot of letters goes inside another.
'go' becomes 'pee' (both can mean to urinate).
'large' becomes 'L' (eg in clothes sizes).
'tr' inserted within 'pee' is 'petre'.
'petre'+'l'='PETREL'
'or' is the link.
(Other definitions for petrel that I've seen before include "Storm bird" , "Bird of storms at sea" , "Seabird sounds like fuel" , "Seabird that flies far from land" , "18's [BIRD]" .)