Observe work in nursery is so unpleasant (3-8)
I believe the answer is:
eye-watering
'nursery is so unpleasant' is the definition.
I can't tell whether this definition defines the answer.
'observe work' is the wordplay.
'observe' becomes 'eye' (eye can mean to observe or see).
'work' becomes 'watering' (I can't justify this - if you can you should believe this answer much more).
'eye'+'watering'='EYE-WATERING'
'in' is the link.
Can you help me to learn more?
(Another definition for eye-watering that I've seen is " Uncomfortably high (like tear gas?)".)