A crafty type cut off from island off Galway (8)
I believe the answer is:
trimaran
'off galway' is the definition.
The definition suggests a singular noun which matches the answer.
'a crafty type cut off from island' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'an' and 'an' is found in the answer.
'cut' could be 'trim' (trim is a kind of cut) and 'trim' is found in the answer.
The remaining letters 'ar' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for trimaran that I've seen before include "Three-hulled boat" , "Three-hulled vessel" , "Sailing boat with three hulls" , "Sailing boat with 3 hulls" , "type of boat" .)