NORTH
 KQ6543
 A32
 7654
 
 T97
 765
 98
 J7654
   A8
 KQJT984
 A
 A32
  J2
 
 KQJT32
 KQT98
Dealer: East    Vul: Both   MP Scoring

West

Pass
Pass
Pass
Pass

North

2
4
6
Pass

East
1
3
X
X
Pass

South
2
4
XX
Pass

 Action 

South at first turn was torn between overcalling 2 and, so short in hearts, preempting with 2N an expected West heart raise that never came.
Aware of the 9+ cards diamond fit, South upgraded 9 HCPs to a forcing 5+ card spade showing 2 bid.
East's fine heart suit was certainly worth at least a favourable vulnerability 3 competing.
South's 2 overcall was limited to no more than 17 points and the 11 cards in the minors, partner spade bid suggesting an upgrading of the J to a full point, and perhaps something in the coffee further compelled a 4 competing.
North cuebid with 4 suggesting slam interest in one of the minors.
East doubled requesting a heart lead.
South somehow found the minimum 4 bid either good enough to redouble to show first round control of hearts.
North somehow decided that one cautious slam try/slam try evasion could to the wind be thrown with the already advertised 10+ HCPs perhaps in view of some extreme South enthusiasm and bid 'the' diamond slam.
East, looking at 3 aces, doubled as most might be expected to do.

A heart was led, won in dummy and a spade discarded.
A small spade was played from dummy and East played low, imagining a South spade void.
South won the now singleton J, ruffed a club, the K and East's A, another club, a heart and a third club, watching East's A tumble.
The KQ were now established and trumps begun and soon ended.

In some cases an A shouldn't be played at trick two.
What are the indictors for and against playing the A at trick one?
If South had had 1 spade, 6 diamonds and 6 clubs, as perhaps the auction suggested, the KQ would have become two club discards if East plays the A at trick one.
Counting clubs around the table given a South 6 club card estimation, East notes West would have 4 (13-3-6=4).
What would South do with the extra spade discard? Would a 2nd spade discard be for a club loser that would probably be just one of a number of club winners established with ruffs just a few ruffs?
If East had had fewer clubs, West would have had more clubs and perhaps there wouldn't be clubs enough.