On holiday in Ottawa yearly (4)
I believe the answer is:
away
'on holiday' is the definition.
(away from one's home)
'in ottawa yearly' is the wordplay.
'in' indicates the answer is hidden within the clue.
'AWAY' is hidden in the letters of 'ottawa yearly'.
(Other definitions for away that I've seen before include "At a distance, from home say" , "Game played at opponents' ground" , "Having started" , "At a distance; match" , "Absent - abroad" .)