enter for something—join for participation in a contest or competition:
- They entered for the national championship but were not good enough.
enter upon something—
1. make a start on an activity:
- As soon as we entered upon the task we realized it was going to be difficult.
2. take up a position; assume duties:
- He enters upon his new appointment at the beginning of June.
3. take possession of smth.:
- She expects to enter upon her inheritance sometime next year.