Up to get this planted over in sunlit nursery (5)
I believe the answer is:
until
'up to' is the definition.
(I've seen this in another clue)
'over in sunlit nursery' is the wordplay.
'over' shows that the letters should be reversed in order.
'in' says the answer is hidden in the clue.
'litnu' is hidden in the letters of 'sunlit nursery'.
'litnu' reversed gives 'UNTIL'.
'get this planted' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for until that I've seen before include "Up to that moment" , "Before a given time" , "As far as" , "Pending such time as" , "As late as" .)