Stick nothing in the middle of the road! (3)
I believe the answer is:
rod
'stick' is the definition.
(both can mean a pole)
'nothing in the middle of the road' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'in the middle of' indicates putting letters inside.
'the road' becomes 'rd' (abbreviation).
'o' put inside 'rd' is 'ROD'.
(Other definitions for rod that I've seen before include "An angler's stick" , "Staff" , "Rigid stick" , "axle" , "Fisherman's item" .)