Bear to carry on (6)
I believe the answer is:
endure
I believe this clue is a double definition.
'bear' is the first definition.
(both can mean to tolerate)
'carry on' is the second definition.
(thesaurus)
'to' is the link.
(Other definitions for endure that I've seen before include "Tolerate, put up with" , "Last or bear with courage" , "Suffer, tolerate" , "Put up with something" , "Abide" .)