British lumberjack in poster (7)
I believe the answer is:
blogger
'poster' is the definition.
(someone who posts on a blog)
'british lumberjack' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'lumberjack' becomes 'logger' (logger is a kind of lumberjack).
'b'+'logger'='BLOGGER'
'in' is the link.
(Other definitions for blogger that I've seen before include "Journal-writer on the internet" , "Person posting personal thoughts on the Internet" , "One writes a journal on the internet" , "One keeps a web log" , "like Guido Fawkes?" .)