This one took a lot of time. However, once I clicked into the 'B' device - which should have been obvious from the outset - the puzzle did come together. 24a caused me some problems, as there is a very similar (and arguably more common) term that might also fall within the definition. Fine with tackling an Enigmatist on a public holiday rather than a work day, and don't quite share the level of grief I'm seeing online - perhaps added to by UK solvers watching the cricket?