Linnaeus maybe wrong in principle - nothing to prevent one seeing clearly (10)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

X (wrong, as in marking students’ work) in TAO (principle) + NO MIST (‘nothing to prevent one seeing clearly’). Carl Linnaeus was a Swedish botanist, physician and zoologist as well as the taxonomist who formalised the modern system of naming organisms.