Firm restricted guests (7,7)
I believe the answer is:
limited company
'firm' is the definition.
The definition and answer can be both groups as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'restricted guests' is the wordplay.
'restricted' becomes 'limited' ('limit' can be a synonym of 'restrict').
'guests' becomes 'company' (I've seen this in another clue).
'limited'+'company'='LIMITED COMPANY'
Can you help me to learn more?
(Other definitions for limited company that I've seen before include "desired by the semi-reclusive?" , "plc" , "business" .)