Happens When One Acts as Substitute

Happens when one acts as substitute crossword clue. A cryptic clues across at the Giant crossword DailyMail on Jun 3, 2017. 10 letters, 2 words (5-5)

The quick clues is happens.

The answer is TAKES PLACE

takes place meaning
(intransitive) To happen, to occur. example: Let me tell you how it happened.
(obsolete) To take precedence or priority. example: Can we find and add a quotation of Addison to this entry?
(obsolete) To take effect; to prevail.