Isle where there's a bad hat to catch (6)
I believe the answer is:
thanet
'isle' is the definition.
(I've seen this before)
'there's a bad hat to catch' is the wordplay.
'there's a bad' is an anagram indicator.
'to catch' becomes 'net' (netting is a kind of catching).
'hat' anagrammed gives 'tha'.
'tha'+'net'='THANET'
'where' acts as a link.
(Other definitions for thanet that I've seen before include "Northeast part of Kent" , "Area of Kent, an island in name only" , "Isle in Kent" , "District of Kent" , "Kent island, scene of many Norse invasions" .)