Once party is over, they may have a deflated look? (8)
I believe the answer is:
balloons
'they may have a deflated look?' is the definition.
The definition suggests an adverb but the answer is not.
'once party is over' is the wordplay.
'once' becomes 'oons' (I can't explain this - if you can you should give a lot more credence to this answer).
'party' becomes 'ball' (ball is a kind of party).
'is over' is a charade indicator (letters next to each other).
'oons' put after 'ball' is 'BALLOONS'.
Can you help me to learn more?
(Other definitions for balloons that I've seen before include "Lighter-than-air aircraft run by hot air" , "Glasses are called for!" , "Inflatable party decorations" , "they give people a lift" , "Party novelties" .)