Old country in Asia Minor (4)
I believe the answer is:
siam
'old country' is the definition.
(I've seen this before)
'in asia minor' is the wordplay.
'in' indicates the answer is hidden within the clue.
'SIAM' is hidden in the letters of 'asia minor'.
(Other definitions for siam that I've seen before include "Thailand's former name" , "old part of East" , "Thailand, formerly" , "An old country" , "Old Thailand" .)