The favourite comes round then takes part in the event (8)
I believe the answer is:
competes
'takes part in the event' is the definition.
Although both the answer and definition are verbs in their -s form, I cannot understand how one could define the other.
'the favourite comes round' is the wordplay.
'the favourite' becomes 'pet' ('pet' can be a synonym of 'favourite').
'round' is an insertion indicator.
'pet' going within 'comes' is 'COMPETES'.
'then' acts as a link.
Can you help me to learn more?
(Other definitions for competes that I've seen before include "Vies" , "Contends for a prize" .)