Marconi for example on Isle of Wight holiday, forgetting a name (8)
I believe the answer is:
inventor
'marconi for example' is the definition.
(Guglielmo Marconi was an inventor)
I can't explain the rest of the clue.
(Other definitions for inventor that I've seen before include "Person originally making" , "Designer" , "eg Rubik" , "The first one to make something" , "Morse, perhaps" .)