Walk with a firm, heavy step (5)
I believe the answer is:
tramp
'walk with a firm heavy step' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tramp that I've seen before include "Trudge; vagrant" , "cargo-boat" , "I might hitch a lift" , "Walk noisily; vagrant" , "sometimes harboured?" .)