Number viewed entertaining contest (9)
I believe the answer is:
seventeen
'number' is the definition.
(seventeen is a kind of number)
'viewed entertaining contest' is the wordplay.
'viewed' becomes 'seen' (to view is to see).
'entertaining' is an insertion indicator (inviting in, as for dinner).
'contest' becomes 'event' (event can mean a sporting competition).
'seen' going around 'event' is 'SEVENTEEN'.
(Other definitions for seventeen that I've seen before include "odd number" , "XVII" , "Age when full driving licence can be obtained" , "Quite a few" , "Figure" .)