23 across
10
bit
something
hard
(10)
10 bit something hard (10)
hints
0
checks
0
hints
The definition is at the beginning of the clue.
How the clue works
The definition is 10, which cross-refers to 10 across (FOOL) — Touchstone being the famous fool in Shakespeare's *As You Like It*. The wordplay is a charade: TOUCH (meaning a little "bit" of something) followed by STONE (meaning "something hard"), giving TOUCHSTONE.