Taking regents or S.A.T.s can be a challenge for high school students.
He wants to challenge you to a race around the track. The diet will be a challenge, but you can do it.
It was a challenge to find the penny in the haystack.
Climbing the mountain would be a challenge but it is possible.
Janet always enjoyed a challenge.The sports challenge looked good this year.I will challenge your decision.
In the sentence that you give, the word challenge is used as a noun.
The nouns in the sentence are party and challenge. The word planning is a gerund, a verbal noun.
The girl is very challengeable as she is very competitive
The word "overweening" is an adjective. An example of a sentence using the word would be: The student was loud, arrogant, and overweening; he proved to be a challenge for his teachers.
the pioneers faced the challenge of settling the frontier with unyielding courage
I knew at the outset of our journey that we had a big challenge ahead of us.
Sam found long division to be a formidable challenge. (here the word means tough)
He balked at the challenge, for it seemed too difficult for him. I knew that she would balk when you screamed at her.