Bidding
East opens 1C, you with 12 points could make a takeout double 'X', but that tells partner you have at least 3 cards in every other suit except clubs and this is clearly not the case. so overcall your 6 card heart suit. 1H, west makes a
negative double saying partner I have values, you rebid your heart suit showing a strong overcalling hand (remember you can have as few as 8 points to overcall). All Pass
Acol Bidding
East opens 1C, you with 12 points could make a takeout double 'X', but that tells partner you have at least 3 cards in every other suit except clubs and this is clearly not the case. so overcall your 6 card heart suit. 1H, west makes a
negative double saying partner I have values, you rebid your heart suit showing a strong overcalling hand (remember you can have as few as 8 points to overcall). All Pass
Dummy goes down and in a suit count your losing tricks. Spades:2, Hearts:1, Diamonds:1, Clubs:2. So you need to develop 2 extra winning tricks to make your contract. How will you do it? Will you play for the drop of KH? or finesse? Will you finesse the QD or overtake with AD and ruff the KD out? So many decisions.
Lose the first 2 tricks to the club leads, then west ruffs your QS winner! over ruff now you can't afford any more losers. Lead out the QS finessing east for the KH planning to lead again from the North hand if east ducks, overtake east's KH and lead a second round of trumps to draw them all out. Lead out the QD and overtake when west plays the KD, good now the JD, TD and maybe 5D will be winners. Play JD, TD and and 5D which loses to 8D. The rest of the tricks are yours. ;-)
You can make 10 tricks if west has KD and east has KH. But you will be 1 trick light if not.