Guiding principle on credit misconstrued (8)
I believe the answer is:
doctrine
'guiding principle' is the definition.
(I've seen this before)
'on credit misconstrued' is the wordplay.
'misconstrued' indicates an anagram.
'on'+'credit'='oncredit'
'oncredit' with letters rearranged gives 'DOCTRINE'.
(Other definitions for doctrine that I've seen before include "Set of religious principles" , "(Church) principles" , "Dogma" , "No credit given for set of beliefs" , "Body of religious teaching" .)