A relation's skewed thinking (9)
I believe the answer is:
rationale
'thinking' is the definition.
(rationale is a kind of thinking)
'a relation's skewed' is the wordplay.
'a relation' can be anagrammed to 'RATIONALE'.
But, I am unsure how this is indicated.
Can you help me to learn more?
(Other definitions for rationale that I've seen before include "Why regulate" , "The logical basis of some thing or action" , "Basis of logic" , "This might account for" , "Underlying principle" .)