Determined to lose true order (8)
I believe the answer is:
resolute
'determined to' is the definition.
(similar in meaning)
'lose true order' is the wordplay.
'order' is an anagram indicator.
'lose'+'true'='losetrue'
'losetrue' with letters rearranged gives 'RESOLUTE'.
(Other definitions for resolute that I've seen before include "without flinching" , "Determined, intent" , "'With fixed purpose, steadfast (8)'" , "Admirably purposeful" , "Purposeful and unwavering" .)