Tolerate with constraint (3)
I believe the answer is:
let
This might be a double definition.
'tolerate' is the first definition.
(I've seen this in another clue)
'constraint' is the second definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe there's an association between them I don't understand?
'with' acts as a link.
Can you help me to learn more?
(Other definitions for let that I've seen before include "Permit or rent" , "Allow - hire" , "Allow or lease" , "Was inclined to ignore" , "hired" .)