Animal in an Eastern country (5)
I believe the answer is:
eland
'animal' is the definition.
(thesaurus)
'an eastern country' is the wordplay.
'an eastern' becomes 'e'.
'country' becomes 'land' ('land' can be a synonym of 'country').
'e'+'land'='ELAND'
'in' is the link.
(Other definitions for eland that I've seen before include "game animal" , "wild creature" , "One browses in the African plain" , "South African antelope" , "Ruminant" .)