Superman’s county (4)
I believe the answer is:
I believe this is a double definition.
'superman's' is the first definition.
(I've seen this in another clue)
'county?' is the second definition.
(I know that Kent is a county)
(Other definitions for kent that I've seen before include "Canterbury's county" , "known in Scotland" , "Garden of England - Superman's family name" , "Lear's faithful Earl" , "English architect and landscape gardener" .)