Staff cross, but half-heartedly (3)
I believe the answer is:
rod
'staff' is the definition.
(both can mean a pole or stick)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for rod that I've seen before include "Long, straight stick" , "Straight, slender stick" , "that most anglers use" , "Little boy" , "Sceptre" .)