I’ve just downloaded an Employment Contract T&C’s template, from an online provider (promoted via one of these HR websites).

The template contains the following condition:

5. Hours of work
Your normal hours of work are between [TIME] and [TIME], [Mondays] to [Fridays] inclusive, with a lunch break
of one hour. You may be required to work such additional hours as are necessary for the proper performance of your duties without extra remuneration.

Is that last line acceptable (legally & ethically)? I should add, I wil not be advocating this condition!