Losing energy, De Niro jeers, barking pointed responses (10)

I believe the answer is:

rejoinders

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

'pointed responses' is the definition.
'rejoinders' can be an answer for 'responses' (rejoinder is a kind of response). I am unsure of the 'pointed' bit.

'losing energy de niro jeers barking' is the wordplay.
'losing' is a deletion indicator.
'energy' becomes 'e' (physics symbol as in E=mc2).
'barking' indicates anagramming the letters ('barking' can informally mean mad).
'de'+'niro'+'jeers'='denirojeers'
'denirojeers' with 'e' taken away is 'dnirojeers'.
'dnirojeers' is an anagram of 'REJOINDERS'.

Can you help me to learn more?

I've seen this clue in The Everyman puzzle in The Observer.

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