Tweet to thwart censure at last (4)
I believe the answer is:
pipe
'tweet' is the definition.
(both can mean to make a high-pitched sound)
'thwart censure at last' is the wordplay.
'thwart' becomes 'pip' (as in pipping someone to the post).
'at last' indicates one should take the final letters.
The final letter of 'censure' is 'e'.
'pip'+'e'='PIPE'
'to' is the link.
(Other definitions for pipe that I've seen before include "chanter" , "Wine cask; sing shrilly" , "11th" , "Part of an organ; tube" , "Fluid or gas transporter" .)