Be close to making a lot of noise about a bit of a joke (6)
I believe the answer is:
adjoin
'bit of a joke' is the definition.
Although both the answer and definition are verbs in their base form, I can't see how one could define the other.
'be close to making a lot of noise about a' is the wordplay.
'be close to' is a charade indicator (letters next to each other).
'making a lot' becomes 'j' (I can't justify this - if you can you should believe this answer much more).
'of' becomes 'o''.
'noise' becomes 'din' (din can mean a loud noise or disturbance).
'about' means one lot of letters goes inside another.
'j'+'o'='jo'
'jo' placed into 'din' is 'djoin'.
'djoin' put after 'a' is 'ADJOIN'.
Can you help me to learn more?
(Other definitions for adjoin that I've seen before include "Meet - touch" , "Be next or nearest to" , "Be next to, say building" , "Lie adjacent to another" , "Neighbour" .)