Poster wanting British lumberjack (7)
I believe the answer is:
blogger
'poster' is the definition.
(someone who posts on a blog)
'wanting british lumberjack' is the wordplay.
'wanting' means one lot of letters go next to another.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'lumberjack' becomes 'logger' (logger is a kind of lumberjack).
'b' put next to 'logger' is 'BLOGGER'.
(Other definitions for blogger that I've seen before include "One writes a journal on the internet" , "Journal-writer on the internet" , "like Guido Fawkes?" , "Online journalist" , "Contemporary diarist" .)