Aspria...
4 letter horse and 2 letter to die around usual abbreviation for Knight. Gives an adjective describing a way of cooking meat that was named after this particular battle...
@andyp: I’m struggling with 17A myself despite the earlier hint.
32D - definition is last 3 words, …………………………
37A - definition is last 2 words, ………………….
NB Post amended by Admin as I am informed it gives away too much in relation to the Theme.