Our convention this week is:

This applies to pairs who play strong-club openings. The generally
accepted system where a double of an overcall is simply point-showing
is a poor method. We suggest that when there's an overcall of your
strong club, you play as if the 1C opening were natural. For example
after the 1 overcall:

pass = could be weak or a trap with spades
double = a standard negative double, promising 4 hearts
1NT = 8-10 and stoppers
2 = a "raise" in clubs (or natural and forcing, your choice)
2 = natural and forcing
2 = natural and forcing
2 = an 11+ point hand with nothing else to bid, denies 4 hearts
2NT = 11+ natural
jumps = weak, long suit

A more sophisticated method is to play 2, 2, and 2 as transfers,
showing diamonds, hearts, and clubs in that order.