I was sure the 1♥ was a psych but I couldn't see us unravelling this, so I just bid 3NT which went + 2, but partner's 7 HCP including 5♥s, ♦J, and doubleton ♠ meant that 6♥ was cold, and half the field bid it, so -9 IMPS.
It seems like this will only happen once every 10 years or so and I'm not too worried about it. It was a gutsy vulnerable 5 HCP psych on a singleton (escape was 6-card ♣ suit).
How would you have approached it?