Carnage in service by Israeli port (8)
I believe the answer is:
massacre
'carnage' is the definition.
(I've seen this before)
'service by israeli port' is the wordplay.
'service' becomes 'mass' (I've seen this in other clues).
'by' is a charade indicator (letters next to each other).
'israeli port' becomes 'Acre' (port in Israel).
'mass'+'acre'='MASSACRE'
'in' acts as a link.
(Other definitions for massacre that I've seen before include "Mass murder" , "Indiscriminate killing of large numbers" , "Slaughter of large number of people" , "Indiscriminate slaughter" , "Murder (of many persons)" .)