The competition is in two trivial parts (5)
I believe the answer is:
rival
'the competition' is the definition.
(thesaurus)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for rival that I've seen before include "Someone you hope to defeat" , "Person in direct competition" , "Contestant you hope to defeat" , "Contender" , "Close competitor" .)