Swear to avoid losing time (4)
I believe the answer is:
aver
'swear to' is the definition.
(I've seen this in another clue)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for aver that I've seen before include "Vera could declare to be true" , "State firmly - even rave about" , "Formally assert" , "'Affirm, assert (4)'" , "State firmly, perhaps rave" .)