Note fish in French sea seem diseased (8)
I believe the answer is:
malinger
'seem diseased' is the definition.
(to malinger is to pretend to be ill)
'note fish in french sea' is the wordplay.
'note' becomes 'a' (musical note).
'fish' becomes 'ling' (ling is a kind of fish).
'in' indicates putting letters inside.
'french sea' becomes 'mer' ('sea' in French).
'a'+'ling'='aling'
'aling' put into 'mer' is 'MALINGER'.
(Other definitions for malinger that I've seen before include "To shirk work" , "Feign illness to avoid work" , "Loaf about in germinal way" , "Loaf or procrastinate" , "skive off school, maybe" .)