Uncompromising, to be exact (5)
I believe the answer is:
rigid
This clue is a double definition.
'uncompromising' is the first definition.
(I've seen this before)
'be exact' is the second definition.
(thesaurus)
'to' is the link.
(Other definitions for rigid that I've seen before include "Frozen" , "Not flexible" , "stern" , "Stiff, unbending" , "unwilling to move" .)