Returning songbird impishly carries bit of leaf (6)
I believe the answer is:
midrib
'leaf' is the definition.
Both the definition and answer are singular nouns.
Maybe you can see an association between them that I don't see?
'returning songbird impishly carries bit' is the wordplay.
'returning' shows that the letters should be reversed in order.
'bit' indicates a hidden word.
'birdim' can be found hidden inside 'songbird impishly carries'.
'birdim' back-to-front is 'MIDRIB'.
'of' is the link.
Can you help me to learn more?
(Other definitions for midrib that I've seen before include "part of leaf" , "Large vein on leaf" , "Central leaf vein" , "Part of leaflet" , "major vein" .)