Might one organise the classroom? (12)
I believe the answer is:
schoolmaster
'might' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'one organise the classroom?' is the wordplay.
'one organise' is an anagram indicator (I've seen 'organised' mean this).
'the'+'classroom'='theclassroom'
'theclassroom' anagrammed gives 'SCHOOLMASTER'.
(Other definitions for schoolmaster that I've seen before include "The classroom (anag)" , "One teaching" , "Male teacher" .)