So here was the hand in question.
you open 1C, lho 1H, partner neg X, rho 3H
What would you do now?
I asked a few people. A world medalist decided to just bid 6S. The player at the other table just bid 4S. A grand life master wanted to bid 4NT blackwood (is it blackwood?), then bid 6S opposite a 1 ace response.
One other possibility was the convoluted auction mentioned in the previous posts. I was pretty sure my partner would read 5D as exclusion keycard for spades, but I also knew that a 1 ace response (5S) would wrong-side the eventual slam. It was just as likely that partner had the ♠A and I should just blast 6S.
After long long thought, I decided to bid exclusion. I figured I could win by staying out of slam when I need to, or if partner had 3+ clubs and we could back into a making 6C, or if partner had a stiff heart which is still not unreasonable given this auction. Partner corrected to 6S, had Axxx xx KJT9x xx, and went down on the heart lead.