1 P
1 P 1♠ P

Counting our top tricks (looking to ‘TEE off’) we have: no spades, 2 hearts, 1 diamond and 3 clubs. Normally you would count 2 top tricks for the clubs here but the lead into our ♣AJxx in hand has actually given us an extra trick on the lead. With 6 top tricks we need to find at least 3 more, and it is clear that our best chance is in the diamond suit. Even if we lose a trick to the missing K then we should still be able to build 3 more tricks through the length and strength of the diamonds on the dummy. Ideally we would like to make all 5 diamonds on the table but to do so we need to avoid losing to the K and the best odds to avoid that are to take the finesse, so that should be our plan here.

So, duck the opening club lead on the dummy to ensure we promote our ♣J in hand and then immediately look to tackle the diamonds by leading a low one from hand. When East plays low (second hand low!) we should finesse with any of the Q, J or 10. When this wins we can mark East with the K and we therefore want to return to hand to do the finesse again. So play a low heart from the dummy and win it in hand with the A or K and play another diamond towards the table. If/when East ducks once again we can finesse with another intermediate honour, noting that everyone played a diamond on the second round too. Counting the diamonds then gives us: 8 played so far, 3 left on the table and 1 left in hand, so there is only 1 diamond left, which must be the K with East. So next cash the A and the other 2 length winners in diamonds, cash the ♣K (unblocking), cross to hand with your last heart honour and cash the ♣A. This should get you to 10 tricks in total with 2 hearts, 5 diamonds and 3 clubs for 3NT+1.

As mentioned earlier, even if the finesse had not worked in diamonds and we had lost a trick there, we are still going to make our contract as long as diamonds are breaking reasonably because we only needed 4 tricks from the diamonds to make here. Carelessly cashing heart or club winners before tackling the diamonds will lead to danger as the defenders can now potentially win length tricks in either of those suits, so your best bet is definitely to start on diamonds as soon as you can.