Lift raincoat to find part of shaft (3)
I believe the answer is:
cam
'part of shaft' is the definition.
(mechanical part)
'lift raincoat' is the wordplay.
'lift' says the letters should be written backwards.
'raincoat' becomes 'mac' (macintosh is a type of raincoat).
'mac' backwards is 'CAM'.
'to find' acts as a link.
(Other definitions for cam that I've seen before include "East Anglian river" , "Irregular projection" , "Projection on a rotating shaft in contact with another part" , "academic stream" , "running through university city?" .)