Clear left turn by detectives (5)
I believe the answer is:
lucid
'clear' is the definition.
(similar in meaning)
'left turn by detectives' is the wordplay.
'left' becomes 'l' (common abbreviation).
'turn' becomes 'u' (a 'U-turn' is a kind of turn).
'by' says to put letters next to each other.
'detectives' becomes 'cid' (abbreviation for Criminal Investigation Department).
'l'+'u'+'cid'='LUCID'
(Other definitions for lucid that I've seen before include "Thinking clearly" , "Able to think clearly" , "Clear, intelligible" , "Rational, clear" , "Bright; sane" .)