Green’s Dictionary of Slang

very severe towards, intent on.

1708		‘Trip to Dunkirk’ in Harleian Misc. I (1808) 211: Nor has the French threats, or their menaces, scar’d us [...] Then since they’re so hot on’t, ’gad let em come, / I’ll warrant they’ll be maul’d.
1855		W.G. Simms Forayers 377: Why were you so hot on his trail, Dick?
1892		J. Newman Scamping Tricks 117: I say, you are hot on the question.
1937		(con. 1905–25) E.H. Sutherland Professional Thief (1956) 76: The government is not so hot on the passers but concentrates on the makers of the counterfeit bills.
1960		J.R. Ackerley We Think The World Of You (1971) 17: The ‘beaks’ were inclined to be ‘’ot’ on what he’d done.
1990		W.D. Myers Mouse Rap 156: ‘I didn’t think he was that hot on finding the treasure’.
1997		G. Sikes 8 Ball Chicks (1998) 121: The police were too hot on them, just then. And they listened.
2001		A. Sillitoe Birthday 108: She was dead hot on that.