A natural hanger-on (4)
I believe the answer is:
burr
'a natural' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
'hanger-on' is the wordplay.
I cannot quite understand how this works, but
'hanger-on' could be 'bur' (type of seed which hangs onto clothing) and 'bur' is located in the answer.
A single letter 'r' remains which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for burr that I've seen before include "Prickly seeds" , "Rough or dialectic pronunciation: rough edge on metal" , "Rough cut edge; West Country accent" , "Rough pronunciation of the letter r as in some areas" , "Rough edge after cutting" .)