Crossword Genius

Clear-headed on trial, a criminal (8)

Ross

I believe the answer is:

rational

'clear-headed' is the definition.
(I've seen this before)

'on trial a criminal' is the wordplay.
'criminal' indicates anagramming the letters.
'on'+'trial'+'a'='ontriala'
'ontriala' is an anagram of 'RATIONAL'.

(Other definitions for rational that I've seen before include "Reasonable - sane" , "Sensible, based on reason" , "Capable of thought" , "Logical; sensible" , "Endowed with reason" .)

I've seen this clue in The Telegraph.
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