West switched to the five of clubs when partner contributed the nine of spades. East topped the queen with the ace to return the ten of spades. West cashed three spades on which East discarded two small diamonds. West continued with king and another club as the defenders won the first nine tricks resulting in a three-trick set, NS -300.
If West mistakenly plays three rounds of spades, South would run for home with seven tricks to score a modest +90. West declined to take any action, most likely because he had no conventional way to show the black suits with longer clubs. E-W could win ten tricks in a club partscore but +130 could not favorably compare with the actual result. Suppose that South opens one diamond, an action that will handcuff West because he holds the wrong pattern for a takeout double (a doubleton heart). A vulnerable two club overcall is hardly suggested but, if he passes as will North, the minor suit opening will end the auction when East declines to balance. East cannot, in good conscience, consider a takeout double holding a measly 7 HCP and a doubleton spade.