Reasoning (5)
'reasoning' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for logic that I've seen before include "Rational thinking" , "Sound sense" , "System of reasoning" , "Reasonable judgement" , "Chain of reasoning" .)
'reasoning' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for rational that I've seen before include "Sensible, based on reason" , "Consistent with reason" , "Logical, reasoned" , "Consistent with logic" , "Having common sense or reason" .)