Crossword Puzzle Org. whose functions follow forms?

Clue: Org. whose functions follow forms?

It often functions with the help of an organ (CHOIR with 5 letters)
Follower or Lenin or Stalin (ISM with 3 letters)
It can follow two hips (HURRAY with 6 letters)
Organ with a lobe (EAR with 3 letters)
Event whose followers are sometimes called bracketeers (MARCHMADNESS with 12 letters)
Fight organizer? (RUMBLERUNNER with 12 letters)
Cough or lemon follower (DROP with 4 letters)
RV follower (TOWCAR with 6 letters)
Work together, as organisms (COACT with 5 letters)
Screen follower? (SAVER with 5 letters)