Redhead almost breaking stick (6)
I believe the answer is:
adhere
'stick' is the definition.
(to adhere to something is to stick to it)
'redhead almost breaking' is the wordplay.
'almost' means to remove the last letter (almost the whole word is kept).
'breaking' indicates an anagram.
'redhead' with its last letter taken off is 'redhea'.
'redhea' with letters rearranged gives 'ADHERE'.
(Other definitions for adhere that I've seen before include "Stick to as by suction" , "Stick to, cling" , "Hold fast, stand by" , "Stay attached" , "Bond" .)