Crossword puzzle clue "reason for action"

It doesn't convey ferocious fuel-burning action, action, action! when it's regular-sized

Reason for action

Piece of the action, or a shout that stops the action

Who said "Action may not always bring happiness, but there is no happiness without action."

Classic reason to call the IT guy #4

Reason the croquet game was called off?

Reason for rehab

Reason for a misunderstanding