Come up against a bill and what goes on it (6)
I believe the answer is:
accost
'come up' is the definition.
(accosting is a kind of coming up)
'against a bill and what goes on it' is the wordplay.
I cannot really see how this works, but
'a' is within the answer.
'bill' could be 'cost' and 'cost' is found in the answer.
A single letter 'c' remains which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for accost that I've seen before include "Tackle" , "Approach boldly or impudently" , "such as a solicitor might do" , "approach with menaces" , "Waylay" .)