Not quite a colleen? (4)
I believe the answer is:
iris
'colleen?' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for iris that I've seen before include "Garden flower - part of eye" , "bloomer?" , "Pupil's place?" , "Pupil is at the centre of this" , "Flag - part of eye" .)