Seat in Commons too limiting (5)
I believe the answer is:
stool
'seat' is the definition.
(stool is a kind of seat)
'in commons too limiting' is the wordplay.
'in' indicates the answer is hidden within the clue.
'STOOL' is hidden within 'commons too limiting'.
(Other definitions for stool that I've seen before include "Small seat" , "Seat without a back" , "Motion" , "Armless seat" , "Backless chair" .)