Fatiguing (6)
'fatiguing' is the definition.
('tire' can be a synonym of 'fatigue')
This is all the clue.
(Other definitions for tiring that I've seen before include "Wearying, exhausting" , "Wearisome" , "Boring" , "Growing weary or bored" , "Becoming sleepy" .)
'fatiguing' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tiresome that I've seen before include "Causing impatience" , "Rather boring" , "Boring, irksome (colloq.)" , "Causing boredom" , "Tedious and boring" .)