Childish feature, using fennel a lot (10)

I believe the answer is:

fontanelle

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'childish feature' is the definition.
The definition and answer can be both body parts as well as being singular nouns.
Perhaps there's an association between them I don't understand?

'using fennel a lot' is the wordplay.
'using' is an anagram indicator (the letters used in a different way).
'fennel'+'a'+'lot'='fennelalot'
'fennelalot' anagrammed gives 'FONTANELLE'.

Can you help me to learn more?

I've seen this clue in The Daily Express.

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