Article written about workers' demo? Of course! (9)
I believe the answer is:
naturally
'of course' is the definition.
(synonyms)
'article written about workers' demo?' is the wordplay.
'article' becomes 'an' (indefinite article).
'written about' shows that the letters should be reversed in order.
'workers'' becomes 'tu' (abbreviation for trade union).
'demo?' becomes 'rally' (rally is a type of demonstration).
'an' back-to-front is 'na'.
'na'+'tu'+'rally'='NATURALLY'
(Other definitions for naturally that I've seen before include "without medicine" , "without medical assistance" , "it goes without saying" , "As a matter of course" , "as anticipated" .)