Sensible person set lair out (7)
I believe the answer is:
realist
'sensible' is the definition.
(thesaurus)
'set lair out' is the wordplay.
'out' indicates an anagram (out can mean wrong or inaccurate).
'set'+'lair'='setlair'
'setlair' anagrammed gives 'REALIST'.
'person' acts as a link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for realist that I've seen before include "One with a pragmatic attitude" , "who may look for practical solution" , "Non-dreamer?" , "Sensible man" , "One who faces things as they are" .)