Drama teacher's diligence (10)
I believe the answer is:
stagecoach
'diligence' is the definition.
(I've seen this before)
'drama teacher's' is the wordplay.
'drama' becomes 'stage' (I can't explain this - if you can you should give a lot more credence to this answer).
'teacher' becomes 'coach' (coach is a kind of teacher).
'stage'+'coach'='STAGECOACH'
Can you help me to learn more?
(Other definitions for stagecoach that I've seen before include "early form of transport" , "Horse-drawn carriage" , "Great Western" , "Diligence" , "Picture of Ford's" .)