Precautions learnt by the way, training bred into little ’uns in the main? (4,5)

I believe the answer is:

kerb drill

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'precautions' is the definition.

'training bred into little 'uns in the main?' is the wordplay.
'training' indicates an anagram (to train can mean to grow something into a shape).
'into' indicates putting letters inside.
'little 'uns in the main?' becomes 'krill' (main can mean sea).
'bred' anagrammed gives 'erbd'.
'erbd' going inside 'krill' is 'KERB DRILL'.

'learnt by the way' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

I've seen this clue in The Guardian.

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