Squid caught malaria at sea! (8)
I believe the answer is:
calamari
'squid' is the definition.
('calamari' can be a synonym of 'squid')
'caught malaria at sea' is the wordplay.
'caught' becomes 'c' (cricket abbreviation).
'at sea' indicates an anagram.
'malaria' with letters rearranged gives 'alamari'.
'c'+'alamari'='CALAMARI'
(Other definitions for calamari that I've seen before include "Squid prepared as food" , "Battered squid rings" , "Mediterranean cooked squid" , "Dish of squid" , "Squid served as food" .)