We have to make some assumptions here.
I deem it unlikely that the contract can be beaten if declarer has the diamond queen and declarer might have played differently at trick one.
Declarer seems to have 4 clubs. With 2=5=2=4 and a small doubleton in diamonds declarer might have rebid 2
♣, so declarer should be 3=4=2=4
The heart 7 is not North lowest heart, so he does not want a heart back and he should not have the heart 8.
It seems to me unlikely that declarer has ducked with both top honors in hearts and no certain entry to his hand any more.
Without the spade ace he might have played on spades first.
If partner has the heart ace we now have 2 heart tricks, a club trick and hopefully a spade trick. This requires partner to have the queen and jack in spades.
The danger is that partner might get forced to play a second heart after three rounds of spades, in which case if we got already a heart a spade and a club, declarer will have no choice but to hope that North has the heart ace.
I envision something like the following layout:
The position after 5 tricks:
In this layout a low spade is fine as is a low diamond. The sapde ten gives away the contract.
However, if dummy puts up the king of spades on a low spade North must unblock to avoid getting end-played.
Switching to the diamond 9 might make it easier for him to do so.
Declarer could have made by going up in hearts immediately, but this was a diffcult play and not clearly indicated.
Rainer Herrmann