What does he have?

Still 2nd set, Woosley-Stewart. Apart from light initials actions going bad, most things go right. Here's a play problem.

K9
AJ84
T6
K8532

AQJT876
T5
8
A95

Stewart opens 1D on my left, playing Precision and after two passes I jump to 4S (white/red). He's not done and comes back with 5D. Freddan bids 5S (instead of X) and I'm left to play it after K-Q of diamonds are led (divides 7-3).

How to go about it? Play for clubs breaking (ditching your heart loser) or getting hearts right for a club discard?

Starting on trumps , LHO shows out 2nd round and we're reached the crossroads. The answer lies in the 5D-bid at unfavourable vulnerability vs a weak hand. That hand must have at least 11 cards in two suit and not an 'empty' secondary suit (i.e. KTxx or similar). So we play on hearts and make the contract.

_______K9
_______AJ84
_______T6
_______K8532
2_____________543
KQ73__________962
AKQ9732_______J54
6_____________QJT4
_______AQJT876
_______T5
_______8
_______A95

Put yourself in opp's position and see what hand(s) would be most likely for the auction.