Uncommonly nice and pure about a bit of rumpy-pumpy? This is being just the opposite (9)

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

Anagram (uncommonly) of NICE + PURE , around the first letter (a bit) of R [umpy-pumpy]. Extended definition: prurience = an unhealthy interest in sexual matters (rumpy-pumpy), rather than a “pure” attitude to them.