Last character, single, in area (4)
I believe the answer is:
zone
'area' is the definition.
(zone is a kind of area)
'last character single' is the wordplay.
'last character' becomes 'z'.
'single' becomes 'one' (I've seen this before).
'z'+'one'='ZONE'
'in' is the link.
(Other definitions for zone that I've seen before include "Section" , "Designated or defined area" , "Region with particular characteristics" , "Area with particular characteristics" , "Particular area or sector" .)