Island making corrupt guy sneer (8)
I believe the answer is:
guernsey
'island' is the definition.
(I've seen this before)
'corrupt guy sneer' is the wordplay.
'corrupt' indicates an anagram (a corrupted form).
'guy'+'sneer'='guysneer'
'guysneer' with letters rearranged gives 'GUERNSEY'.
'making' is the link.
(Other definitions for guernsey that I've seen before include "One of the Channel Islands" , "Second-largest Channel Island" , "Sir Walter Scott novel" , "Lower" , "Lyric poem" .)