Journalist is on drink (8)
I believe the answer is:
reporter
'journalist' is the definition.
(I've seen this before)
'on drink' is the wordplay.
'on' becomes 're' ('on' can be mean 'with reference to').
'drink' becomes 'porter' (porter is a kind of drink).
're'+'porter'='REPORTER'
'is' is the link.
(Other definitions for reporter that I've seen before include "Hack" , "News gatherer" , "News journalist" , "One writes or tells the news" , "One may write a column" .)