Minor punishment for key anxiety, we hear (9)
I believe the answer is:
detention
'minor punishment' is the definition.
'detention' can be an answer for 'punishment' (I've seen this before). I am not certain of the 'minor' bit.
'key anxiety we hear' is the wordplay.
'key' becomes 'de' (I can't justify this - if you can you should give a lot more credence to this answer).
'anxiety' becomes 'tension' (I've seen this before).
'we hear' indicates a 'sounds like' (homophone) clue.
'tension' sounds like 'tention'.
'de'+'tention'='DETENTION'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for detention that I've seen before include "After-school punishment" , "Arrest; school punishment" , "Custody" , "Confinement" .)