Burdensome
'burdensome' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for onerous that I've seen before include "Heavy and hard to bear" , "Burdensome as duty may be" , "Burdensome, oppressive" , "Burdensome, taxing" , "Difficult, troublesome" .)
'burdensome' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for arduous that I've seen before include "Backbreaking" , "Requiring hard work" , "Punishing" , "Requiring much effort" , "Tough" .)
'burdensome' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for weighty that I've seen before include "having great influence" , "substantial" , "Heavy - very serious" , "Important" , "Cumbersome" .)
(Other definitions for stressful that I've seen before include "Causing mental tension" , "under great pressure" , "Worrying" , "Creating tension" , "tense" .)
'burdensome' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for oppressive that I've seen before include "Harsh, authoritarian" , "Sultry" , "cruel" , "Tyrannical" , "Difficult to bear" .)
'burdensome' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tiring that I've seen before include "Wearying, exhausting" , "Becoming sleepy" , "Exhausting or tedious" , "Boring" , "Laborious" .)