Thanks for all the well-considered responses.
I bid 2
♣ on the first round of the auction. Absent explicit discussion to the contrary, I assumed this was forcing. I guess it's possible to play it NF but I know we hadn't discussed any such treatment.
I wish I had considered the 2
♠ cue on the 2nd round of the auction. Holding
♠AJ, I definitely wanted notrump played from my side. Had I bid 2
♠, I don't know if my partner would have found a club bid with her
♣Qx. (I would like to think so, but maybe she'd interpret 2
♣ followed by 2
♠ as a strong hand with some clubs but uncertain about final strain, which is not what I have.)
Partner's actual hand, as divined by mikeh, was 2=5=4=2. It was something like
Back to the actual auction, over partner's 2
♦ call I just bid 6NT. The grand is makeable double-dummy, but the clubs are 5-0 on your left so you have to start the suit by leading low to the 8 (or running the 10 or 9, I guess), finessing into the overcaller. Yeah, right.
This might be a more interesting problem if my RHO had not been insane. She bid 1
♠ on essentially
♠Q-seventh and out. If she had passed we could have a simple constructive auction, but if she'd bid 3
♠ I have to pretty much commit to slam without knowing much about partner's hand. Or do I?