NORTH KJT92 4 Q83 AQ84 A75 KT2 KT962 T7 Q43 953 4 KJ9652   86 AQJ876 AJ75 3

Dealer: South    Vul: None   MP Scoring West 2 Pass Pass Pass North 2 3 3N East Pass X 1 Pass South 1 2N 3 2 Pass

West was obedient to East's lead directing double (of 3) with the T.
Declarer considered the auction and probabilities: North South had combined 24 HCP, West required an opening hand to overcall 2 and East might be expected to have 5+ clubs including at least the KJxxx(xx).
At matchpoints, if East held 7 clubs, winning the first club would be best.
If holding 5 clubs, if the first trick were won, if East had no other entry, West would have to lead clubs through twice more to establish East's club suit.
However, given East had doubled with top three club values being at best KJ9 (declarer could see at trick one West's T and dummy's AQ8), the a priori relative odds of West's being dealt a 5 card suit rather than a 6 card suit might be roughly calculated via radio buttons 8, 8 and 12 then find button at http://www.rpbridge.net/xsb2.htm and summation to be perhaps
35.21 : 20.54 : 5.03 for East's club length scenarios 5:6:7

While a 5 card suit, assumed exactly 5 diamonds with West and 1 with East, is more likely, the implication of the 3 double's suit length/quality requirements may well suggest East better relied upon for 6 club cards.

In the case of 6 clubs, ducking the first club lead is best and East will be held to one club trick.

As it was, the A was won at trick one. Assuming East has then both K and J, remaining for West to have for a 2 bid would be 12 HCP. If absent the K, then 9 points would for a suit missing at least the AQJ8753 have been the case.
West was assumed the K. South won A at trick two and had to decide if West's K was originally doubleton or tripleton.
If the former, then exiting a small heart is right. If the latter, at trick 3 leading the J looks right.
Has all been banked on East's having 5 clubs?

Back to the suit division calculator
Assuming diamonds 5:1 West:East and clubs 2:6 West:East, entering 6, 6, 6, Find in that webpage suggests of 6 card heart divisions comparatively:
24.35 : 43.29 (2West :4East : 3West:3East).
Of course West might have had a 6th diamond (6, 5, 7, Find) 37.88 : 37.88 or a 3rd club(6, 5, 7, Find) 37.88 : 37.88 or perhaps even both (6, 4, 8, Find) 45.45 : 24.24

Declarer decided to play for a 2:4 West:East heart division, perhaps committed to the trick one choice and simply ducked a heart to West's T, not impressing spectating dummy.
West continued a club, East winning KJ and exiting a spade to West's A for in total 2 clubs, 2 hearts and two hearts: 3N down two.

   8>   1.83        1.83  5.92  0.08  3.58  4.75      
         -50   ----  -50   430  -100   100   400   ----

From: http://www.rpbridge.net/xsb2.htm : A Bridge Toy by Richard Pavlicek