Looks more like velvet. All fish (not just the one) need to be moved to a quarantine, treated with copper powder at therapeutic levels for 30 days, and your display tank needs to sit fallow for a minimum of 76 days. And this needs to be done quickly as velvet is a very fast killer
For clowns, we always tend to lean toward Brooklynella aka Clownfish disease. Early Brook can present like ich or velvet, thus making first diagnosis tricky. Can we get another picture that is less blurred and under all white lighting?