I'm amazed about king entering African country's sporting event (8)
I believe the answer is:
gymkhana
'sporting event' is the definition.
(type of Indian sporting event)
'i'm amazed about king entering african country's' is the wordplay.
'i'm amazed' becomes 'my' (expression of surprise).
'about' says the letters should be written in reverse.
'king' becomes 'K' (abbreviation for king in chess).
'entering' means one lot of letters goes inside another.
'african country' becomes 'ghana' (country in Africa).
'my' backwards is 'ym'.
'ym'+'k'='ymk'
'ymk' going within 'ghana' is 'GYMKHANA'.
(Other definitions for gymkhana that I've seen before include "Meet at which riders and horses display skills" , "Riding event" , "series of competitions" , "Meeting of riders and horses to display skills" , "Field day for equestrians" .)