Single article on period watch (9)
I believe the answer is:
timepiece
'watch' is the definition.
(thesaurus)
'single article on period' is the wordplay.
'single article' becomes 'piece' (I've seen this before).
'on' is a charade indicator (letters next to each other).
'period' becomes 'time' (time is a kind of period**).
'piece' after 'time' is 'TIMEPIECE'.
(Other definitions for timepiece that I've seen before include "alarm, perhaps" , "non-striker?" , "hunter, perhaps" , "Maybe watch" , "Watch, say" .)