HiloHarry Comments:
- Partner should have about seven HCP. You have 12, dummy has five, declarer has about 16. 40 minus (12+5+16) equals seven.
- Declarer seems to have five hearts. Why else would partner part with an honor?
- You can see that declarer started with exactly two clubs, since she opened the bidding 1NT. You started with four clubs, dummy has six clubs, partner showed up with one club. That leaves only two clubs for declarer. Based on your count, you play the ace of clubs to isolate dummy.