Is not quick to pay attention about broken flaps (4,5)

I believe the answer is:

half speed

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'is not quick' is the definition.
I can't judge whether this defines the answer.

'pay attention about broken flaps' is the wordplay.
'pay attention' becomes 'heed' (I've seen this before).
'about' is an insertion indicator.
'broken' indicates an anagram.
'flaps' anagrammed gives 'alfsp'.
'heed' enclosing 'alfsp' is 'HALF SPEED'.

'to' is the link.

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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