Tolerated as well in staid surroundings (5)
I believe the answer is:
stood
'tolerated' is the definition.
('stand' can be a synonym of 'tolerate')
'as well in staid surroundings' is the wordplay.
'as well' becomes 'too' (both can mean 'also').
'in' means one lot of letters goes inside another.
'staid surroundings' becomes 'sd' (I can't justify this - if you can you should give a lot more credence to this answer).
'too' placed into 'sd' is 'STOOD'.
Can you help me to learn more?
(Other definitions for stood that I've seen before include "Remained upright" , "Was upstanding" , "Rose to one's feet" , "Tolerated; stayed upright" , "Was situated" .)