Hopping mad freebooter lost his head (5)
I believe the answer is:
irate
'hopping mad' is the definition.
(I've seen this in another clue)
'freebooter lost his head' is the wordplay.
'freebooter' becomes 'pirate' (pirate is a kind of freebooter).
'lost his head' means to remove the first letter.
'pirate' with its first letter taken away is 'IRATE'.
(Other definitions for irate that I've seen before include "Boiling" , "ranting" , "having got in wax" , "Extremely angry" , "Hacked off" .)