Surgical bypass tube (5)
I believe the answer is:
shunt
'surgical bypass tube' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for shunt that I've seen before include "Rear end collision" , "Transfer rolling stock from track to track" , "Transfer a train to another track" , "Divert into alternative course, like train" , "Car crash (slang)" .)