2S being in 3rd position was wide ranging from total trash to even a reasonable opening hand.
Opps played Leb so 3D shows some values.
You lead your only spade and P wins the first trick with the 9S and continues with the JS taken by Declarers Ace. The JS is a strong side suit preference signal for clubs assuming he started with KQJ9xx
Declarer now cashes the AD to which your P plays the 2D and then forwards the JD.
You appear to have two options now:-
1. Duck and play P for Tx in the suit, thus giving your side a guard and chance to let P in with the likely AC (based on the signal)
2. Cover and play Declarer for AJT and thus block the suit, or be allowed to win the trick in which case you play a club next
I welcome comment on:- If you believe your P should or should not play the TD in this position when he has it / if this is obvious or not
Benefits include:
Plus... it's free!