Seat in the south of central Spain (4)
I believe the answer is:
sofa
'seat' is the definition.
(sofa is a kind of seat)
'south of central spain' is the wordplay.
'south' becomes 's' ('S' can be a synonym of 'south').
'central' indicates the central letters.
The middle letter of 'spain' is 'a'.
's'+'of'+'a'='SOFA'
'in the' is the link.
(Other definitions for sofa that I've seen before include "Oafs (anag.)" , "Living room seat" , "Upholstered seat for more than one person" , "Settee" , "Somewhere to sit" .)