Those "discussions" come up with a couple of solutions - both being to use a separate code for the pausable clock.
I'm not sure that this is required in SFML as "it's pretty trivial to implement this by oneself" and would go along with other stuff that you use all the time but isn't a part of SFML.
more often than not games can be paused and resumed as well, and this usually needs some internal timers to be paused when the game pauses and resumed later.
Pausing the game means pausing the game logic but not necessarily time, as menus (for example) may require animations.
Since you'll probably end up creating and reusing timestep code anyway, why not add your pausable clock (if you still need it) to be included with your timestep code?
It would be odd for me to not mention my small timing library,
Kairos, which - amongst other things - provides pausable clocks (including one which can have its speed altered - including backwards!), and also timestep simplification.