Rod will be loyal! (5)
I believe the answer is:
stick
'rod' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for stick that I've seen before include "Join firm" , "Switch < put up" , "heavy criticism" , "Glue; piece of wood" , "Flak - cling" .)