OAP racing around tree bearing enclosed fruit (9)

I believe the answer is:

angiocarp

I'm a little stuck... Click here to teach me more about this clue!

'enclosed fruit' is the definition.
The definition and answer can be both plants as well as being singular nouns.
Perhaps you can see a link between them that I don't see?

'oap racing around tree bearing' is the wordplay.
I cannot quite understand how this works, but
'around' could be 'ca' (circa) and 'ca' is found within the answer.
'bearing' could be 'n' (north is a compass bearing) and 'n' is located in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Independent.

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