Factors in heartless creature having rival regularly ejected (8)
I believe the answer is:
criteria
'factors' is the definition.
The definition and answer can be both related to thinking as well as being plural nouns.
Perhaps you can see an association between them that I can't see?
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for criteria that I've seen before include "Principles for decision" , "'Standards, reference points (8)'" , "Principles or standards by which to judge" , "Canons" , "Benchmarks" .)