By word of mouth, when you gather round beforehand (6)
I believe the answer is:
orally
'by word of mouth' is the definition.
(I've seen this before)
'gather round beforehand' is the wordplay.
'gather' becomes 'rally' (rallying is a kind of gathering**).
'round' becomes 'o' (round can mean a round object).
'beforehand' means one lot of letters go next to another.
'rally' put after 'o' is 'ORALLY'.
'when you' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for orally that I've seen before include "given by mouth" , "By (word of) mouth" , "By spoken word" , "How anyone would speak" , "How one speaks" .)