One having seat in AA, partner dishevelled Irishman brought in (15)

I believe the answer is:

parliamentarian

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'one having seat' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.

'in aa partner dishevelled irishman brought in' is the wordplay.
'dishevelled' indicates anagramming the letters.
'irishman' becomes 'liam' (common Irish name).
'brought in' is an insertion indicator.
'in'+'aa'+'partner'='inaapartner'
'inaapartner' is an anagram of 'parentarian'.
'parentarian' enclosing 'liam' is 'PARLIAMENTARIAN'.

Can you help me to learn more?

(Other definitions for parliamentarian that I've seen before include "elected representative?" , "Eg, an MP" , "legislator" , "politician" .)

I've seen this clue in The Telegraph.

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