Stop house officer discharging the last two (9)
I believe the answer is:
semicolon
'stop' is the definition.
(I've seen this before)
'house officer discharging the last two' is the wordplay.
I cannot really understand how this works, but
'house' could be 'semi' (short for semi-detached) and 'semi' is found in the answer.
'officer' could be 'col' (short for colonel) and 'col' is located in the answer.
The remaining letters 'on' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for semicolon that I've seen before include "used by writers for a break" , "Joiner" , "Punctuation mark denoting a pause in a sentence" , "Item of punctuation" , "half a stop" .)