Join anonymous objection (4)

I believe the answer is:

abut

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'join' is the definition.
(abut can mean to join or be adjacent to)

'anonymous objection' is the wordplay.
'anonymous' becomes 'a' (this could be a standard abbreviation I've not previously seen).
'objection' becomes 'but' (as in 'no ifs, no buts').
'a'+'but'='ABUT'

Can you help me to learn more?

(Other definitions for abut that I've seen before include "Adjoin, touch" , "Tuba (anag)" , "Meet" , "Of building or land, end or lean against" , "Neighbour" .)

I've seen this clue in The Independent.

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