In spoken language, ordinary gathering (6)
I believe the answer is:
orally
'in spoken' is the definition.
'orally' can be an answer for 'spoken' (I've seen this before). I am unsure of the 'in' bit.
'language ordinary gathering' is the wordplay.
'language ordinary' becomes 'o' (I can't explain this - if you can you should give a lot more credence to this answer).
'gathering' becomes 'rally' (rally is a kind of gathering).
'o'+'rally'='ORALLY'
Can you help me to learn more?
(Other definitions for orally that I've seen before include "How one speaks" , "via the trap" , "By spoken word" , "as auditions are done" , "given drugs thus?" .)