Heavy long-handled hammer (6)
I believe the answer is:
sledge
'heavy long-handled hammer' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sledge that I've seen before include "Vehicle for use in snow" , "Vehicle on runners, for snow and ice" , "Make offensive remarks" , "Sleigh" , "one could go downhill fast" .)