Undermine head teacher, getting clergyman to take public transport over (7)
I believe the answer is:
subvert
'undermine' is the definition.
(synonyms)
'head teacher getting clergyman to take public transport over' is the wordplay.
'head teacher getting' becomes 't' (I can't explain this - if you can you should give a lot more credence to this answer).
'clergyman' becomes 'rev' (short for reverend).
'to take' means one lot of letters go next to another.
'public transport' becomes 'bus' (bus is a kind of public transport).
'over' says the letters should be written in reverse.
't'+'rev'+'bus'='trevbus'
'trevbus' back-to-front is 'SUBVERT'.
Can you help me to learn more?
(Other definitions for subvert that I've seen before include "Cause the downfall of; undermine" , "upset" , "Undermine (someone's authority)" , "Morally corrupt" , "Sabotage" .)