Barking dogs alert experienced person (3,6)

I believe the answer is:

old stager

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'experienced person' is the definition.
'old stager' can be an answer for 'person' (old stager is a kind of person). I'm not sure about the 'experienced' bit.

'barking dogs alert' is the wordplay.
'barking' indicates an anagram (UK slang for mad).
'dogs'+'alert'='dogsalert'
'dogsalert' anagrammed gives 'OLD STAGER'.

Can you help me to learn more?

(Other definitions for old stager that I've seen before include "expert" , "senior citizen" , "One who's experienced a lot" , "veteran" .)

I've seen this clue in The Telegraph.

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