Is this a straight flush?
Python 2, 95 bytes



lambda a:any(set('A234567891JQKA'[i/4:][:5])&lt;={r['HCSD'[i%4]in r]for r in a}for i in range(40))


Try it online!

There are 40 possible straight flushes, and this simply checks them all. Chas Brown saved 2 bytes; Jo King saved 4 more.