I defame Manxman, perhaps (8)
I believe the answer is:
islander
'manxman perhaps' is the definition.
(resident of the Isle of Man)
'i defame' is the wordplay.
'defame' becomes 'slander' ('slander' can be a synonym of 'defame').
'i'+'slander'='ISLANDER'
(Other definitions for islander that I've seen before include "Man of Aran, say" , "Inhabitant of Fiji, for example" , "One living surrounded by water" , "Inhabitant of Skye, say" , "E.g. Shetland inhabitant" .)