Singing challenge in middle of 'Mikado' excited Korea (7)
I believe the answer is:
karaoke
'singing challenge' is the definition.
(karaoke is a singing competition)
'middle of mikado excited korea' is the wordplay.
'middle of' indicates the central letters.
'excited' indicates anagramming the letters.
The centre of 'mikado' is 'ka'.
'korea' anagrammed gives 'raoke'.
'ka'+'raoke'='KARAOKE'
'in' acts as a link.
(Other definitions for karaoke that I've seen before include "Often cringeworthy and drunken singing to a video tape" , "Singing to backing music" , "Amateur singing entertainment" , "Amateur singing to recorded music in bars and clubs" , "Singing to background recording" .)