Legislators a chap has to check out (6)

I believe the answer is:

senate

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'legislators a chap' is the definition.
I can't judge whether this defines the answer.

'has to check out' is the wordplay.
'has to' becomes 'nat' (I can't justify this - if you can you should believe this answer much more).
'check' becomes 'see' (synonyms).
'out' indicates putting letters inside.
'nat' put into 'see' is 'SENATE'.

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(Other definitions for senate that I've seen before include "Legislative body" , "Upper council of university" , "Upper assembly of US" , "State assembly" , "The upper house in parliament or oireachtas" .)

I've seen this clue in the Evening Standard.

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