Rider Haggard's work reflected island author (7)
I believe the answer is:
shelley
'author' is the definition.
(I have seen 'Author of Frankenstein' mean 'shelley' so perhaps 'author' could also mean 'shelley')
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for shelley that I've seen before include "Writer of To a skylark" , "Author of Frankenstein" , "Ode to the West Wind poet" , "English Romantic poet" , "Percy Bysshe . . . . . . ., great English poet" .)