If you play weak two's, open 2S with 7 HCP and a 6 card spade suit, partner raises you to 4S.
Acol Bidding
If you play weak two's, open 2S with 7 HCP and a 6 card spade suit, partner raises you to 4S.
Plan Before You Play
Dummy goes down and you count your losers - AS AC and maybe KD and QD, so 4 of them. The only way to make three diamond tricks is for the opposition to lead away from their diamond honor, hopefully promoting the 10D and JD. (So try not to lead the diamond suit for as long as possible)
The Play
Cover the KH lead and lead a low spade from dummy the AS appears, a diamond is returned play low and hope the JD is made. Lead QS from dummy, ruff a low heart in hand, draw the rest of the outstanding trumps. Lead a low club to KC the AC covers, win the club return and play your last club throwing away a diamond in dummy. Lead a low diamond to the AD, the ruff a heart if east discards their last dummy then the 10D becomes good!
Comment
Making this 4S depends on squeezing the opposition to discard cards in a suit that you need to develop winners in. The trick here was to discard a diamond on the table (not AD) fooling them that you were only going to play 1 more round of diamonds (the opposition if they have not been counting the diamond suit will be unaware you have 10D in hand)
The above commentary is intended as a guideline only. As with any Bridge hand there are many ways to bid and play any hand.