Decided to be resolute (10)
I believe the answer is:
determined
This clue is a double definition.
'decided' is the first definition.
(synonyms)
'resolute' is the second definition.
(similar in meaning)
'to be' is the link.
(Other definitions for determined that I've seen before include "Firmly decided" , "Decided - resolute" , "firm" , "Resolved" , "With full strength and concentration" .)