Bill about to divide ballot for lawyer (8)
I believe the answer is:
advocate
'lawyer' is the definition.
(advocate is a kind of lawyer)
'bill about to divide ballot' is the wordplay.
'bill' becomes 'ad' (advertisement stuck on wall).
'about' becomes 'ca' (abbreviation for 'circa').
'to divide' means one lot of letters goes inside another (some letters create a division in others).
'ballot' becomes 'vote' (synonyms).
'ca' going inside 'vote' is 'vocate'.
'ad'+'vocate'='ADVOCATE'
'for' acts as a link.
(Other definitions for advocate that I've seen before include "Person who pleads on behalf of another, like barrister" , "One pleads a cause" , "Argue for" , "barman" , "Speak in favour of" .)