Book Scottish island up for poet (7)
I believe the answer is:
shelley
'poet' is the definition.
(Percy Bysshe Shelley 1792-1822)
'book scottish island up' is the wordplay.
'book' becomes 'she' (I've seen this before).
'scottish island' becomes 'yell' (one of the Shetland islands).
'up' is a reversal indicator (in down clue: letters go upwards).
'yell' backwards is 'lley'.
'she'+'lley'='SHELLEY'
'for' acts as a link.
(Other definitions for shelley that I've seen before include "Author of Frankenstein" , "Ode to the West Wind poet" , "Mary - - (Gothick writer)" , "Percy Bysshe . . . . . . ., great English poet" , "English Romantic poet" .)