Buckle under bear (5)
I believe the answer is:
yield
This clue is a double definition.
'buckle under' is the first definition.
(synonyms)
'bear' is the second definition.
(I know that bear can be written as yield)
(Other definitions for yield that I've seen before include "Succumb" , "Give way; produce" , "Surrender; output" , "Part with" , "Relinquish" .)