How erotic is a sauna? (6)
I believe the answer is:
steamy
I believe this is a double definition.
'how erotic' is the first definition.
(steamy can mean very erotic)
'is a sauna?' is the second definition.
(a sauna is steamy)
(Other definitions for steamy that I've seen before include "Hot and humid - erotic" , "Salacious" , "Erotic, sexy" , "Erotic - vaporous" , "Vaporous: lustful" .)