Put "To execute, behead" (3)
I believe the answer is:
lay
'put' is the definition.
(as in laying or putting something down)
'execute behead' is the wordplay.
'execute' becomes 'slay' (I've seen this in another clue).
'behead' means to remove the first letter (I've seen 'beheaded' mean this (the head of the word is removed)).
'slay' with its initial letter removed is 'LAY'.
'to' acts as a link.
(Other definitions for lay that I've seen before include "Unprofessional" , "Put down (in position)" , "Place (bet)" , "Not ordained into clergy" , "located" .)