Girl originally from Hebridean island (5)
I believe the answer is:
fiona
'girl' is the definition.
'originally from hebridean island' is the wordplay.
'originally' indicates taking the first letters.
'hebridean island' becomes 'iona' (island of the Hebrides).
The initial letter of 'from' is 'f'.
'f'+'iona'='FIONA'
(Other definitions for fiona that I've seen before include "Girl's name (not Flora)" , "Girl's name, meaning fair in Gaelic" , "Girl" .)