Naturally disposed toward losing the head with checkmate (6)
I believe the answer is:
ending
'checkmate' is the definition.
(thesaurus)
'naturally disposed toward losing the head' is the wordplay.
'naturally disposed toward' becomes 'tending' (I've seen this before).
'losing the head' means to remove the first letter.
'tending' with its first letter removed is 'ENDING'.
'with' is the link.
(Other definitions for ending that I've seen before include "Cessation" , "Putting a stop to" , "terminal" , "Bringing to a close" , "Finish" .)