Posh bores dressed like Elizabethan gents run by that establishment (2-5)
I believe the answer is:
in-house
'posh' is the definition.
Both the definition and answer are adjectives.
Maybe they are linked in a way I don't understand?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for in-house that I've seen before include "Within the organisation" , "Within a company" .)