Middle east country is backing king (6)
I believe the answer is:
israel
'middle east country' is the definition.
(I've seen this before)
'is backing king' is the wordplay.
'backing' says the letters should be written backwards.
'king' becomes 'lear' (King Lear).
'lear' in reverse letter order is 'rael'.
'is'+'rael'='ISRAEL'
(Other definitions for israel that I've seen before include "Middle-Eastern country" , "Country of E. Med" , "Middle Eastern state" , "Strange serial country" , "Eastern Med nation" .)