A leafy, French spinach or pain of some duration (6)
I believe the answer is:
orache
'a leafy french spinach' is the definition.
The answer and definition can be both plants as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'or pain of some duration' is the wordplay.
I cannot quite understand how this works, but
'or' is found in the answer.
'pain' could be 'ache' (ache is a kind of pain) and 'ache' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for orache that I've seen before include "spinach substitute" , "Edible spinach-like plant of the genus Atriplex that thrives in arid areas" , "vegetable" .)