I would tag it as playground=spinningwheel, as this would follow the scheme playground=basketrotator, found the on the wiki page for [playground](https://wiki.openstreetmap.org/wiki/Key%3Aplayground). If you are editing in iD, you will find a header "All Tags" in the left pane, where you can add any tag you want.
I would remove the name:en tag, as it is not name Spinnning Wheel, it a spinning wheel. We also do not map benches with name=Bench. (explained better in [name is the name only](https://wiki.openstreetmap.org/wiki/Names#Name_is_the_name_only).
Normally you can use [any tag tag you want[(https://wiki.openstreetmap.org/wiki/Any_tags_you_like), want](https://wiki.openstreetmap.org/wiki/Any_tags_you_like), but in order to get traction, it is best to document new tags that you invent. If you are sure spinning wheel is the correct Britsh-English word for the toy you could simply add it to the [playground](https://wiki.openstreetmap.org/wiki/Key%3Aplayground) wiki page.
However, for more complex proposals or in case you are not sure about the British English word, you could contact the [tagging mailing list](https://lists.openstreetmap.org/listinfo/tagging) for help.
