Restricted, as some companies? (7)
I believe the answer is:
limited
'restricted' is the definition.
('limit' can be a synonym of 'restrict')
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for limited that I've seen before include "Confined within bounds" , "Finite - type of company" , "was restricting" , "Restricted in extent/size" , "plc" .)