Possible Clues:

• '... and that's final!'
• Time when there's rising anger in school
• It may end a sentence
• One of three in hockey
• Certain 36-Across
• Will the fairy do it up at the end of the sentence?
• It's time to come to the end of your sentence
• Interval of time or a full stop
• Full stop or time interval
• Stretch - cycle