Tough and unbending (5)
I believe the answer is:
stiff
I believe this is a double definition.
'tough' is the first definition.
(I've seen this before)
'unbending' is the second definition.
(I've seen this in another clue)
'and' is the link.
(Other definitions for stiff that I've seen before include "Awkward" , "Frigid" , "Starched, rigid" , "Not giving" , "18 [HARD]" .)