Clue: In one class where everything is the same (10)
Answer: UNIFORMITY
Explanation: Definition: In one class
I think this is supposed to be a double definition, but again the two meanings are the same, and in any case "in one class" would define "uniform", so maybe it's a long cryptic def. *See comments: the consensus seems to be that it's actually FORM 1 or 1 FORM in UNITY (one), which makes it a better clue than I thought; but one of the Is seems be unaccounted for, unless FORM 1 = "(unspecified) class (in a school)"