Lecherous female took chair by unknown artist (6)
I believe the answer is:
satyra
'lecherous female' is the definition.
(female satyr)
'took chair by unknown artist' is the wordplay.
'took chair' becomes 'sat' (sat in a chair).
'by' says to put letters next to each other.
'unknown' becomes 'y' (algebra).
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'sat'+'y'+'ra'='SATYRA'
(Other definitions for satyra that I've seen before include "female deity" , "Lecherous female" .)