Ajar, in poetry (3)
I believe the answer is:
ope
'ajar in poetry' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ope that I've seen before include "Literary form of open" , "Unlock, undo (poetic)" , "moon about, missing maiden" , "Undo, unfold (poetic)" .)