Play low. Partner won’t have the ♠KQ (he would have led high). Since declarer has a spade honor, playing the jack can’t be right. If you play it, declarer can win and then finesse the ♠10 to get rid of a losing heart on the ♠A (if declarer had ♠Qx, the jack does no better). 

	A105  J876  2  KQ876
Q97  K1094  Q9854  3		J8642  AQ5  A1063  4
	K3  32  KJ7  AJ10952