This convention is alertable.
Drury is a convention, used by a passed hand after a major suit opening. It is activated by the following sequence:
/ - 1♥/1♠ - 2♣!
The 2♣ shows 10-12 points and a fit. Afterwards, opener bid 2♦ with a sub-minimal hand, or a hand which is not suitable for any other bid, and all other bids show a full opening value.