Absolutely low on alcohol at gathering (9)
I believe the answer is:
literally
'absolutely' is the definition.
(I've seen this before)
'low on alcohol at gathering' is the wordplay.
'low on alcohol at' becomes 'lite' (I can't justify this - if you can you should give a lot more credence to this answer).
'gathering' becomes 'rally' (rally is a kind of gathering).
'lite'+'rally'='LITERALLY'
Can you help me to learn more?
(Other definitions for literally that I've seen before include "Not figuratively" , "According to the precise meaning of words" , "Actually, really" , "Without exaggeration" , "Exactly as stated" .)