Acting sad when describing prom gone wrong (9)
I believe the answer is:
temporary
'acting' is the definition.
(similar in meaning)
'when describing prom gone wrong' is the wordplay.
'when' becomes 'teary' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'describing' is an insertion indicator (describe can mean to form the outline of).
'gone wrong' indicates anagramming the letters.
'prom' anagrammed gives 'mpor'.
'teary' going around 'mpor' is 'TEMPORARY'.
'sad' acts as a link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for temporary that I've seen before include "not for good" , "Portray me as being for a limited time only" , "For a short period only" , "Not for long" , "Stopgap" .)