Prim artiste clad in tatters (6-5)
I believe the answer is:
strait-laced
'prim' is the definition.
(synonyms)
'artiste clad in tatters' is the wordplay.
'in tatters' is an anagram indicator (I've seen this in other clues).
'artiste'+'clad'='artisteclad'
'artisteclad' anagrammed gives 'STRAIT-LACED'.
(Other definitions for strait-laced that I've seen before include "Prudish" , "Strictly moral" , "Having strict morals" , "Narrow-minded" .)