Performer at rest, I suspect (7)
I believe the answer is:
artiste
'performer' is the definition.
(an artiste is a performer or entertainer)
'at rest i suspect' is the wordplay.
'suspect' indicates anagramming the letters (a suspicious or unusual spelling).
'at'+'rest'+'i'='atresti'
'atresti' is an anagram of 'ARTISTE'.
(Other definitions for artiste that I've seen before include "Attires (anag.)" , "Attires for professional entertainer" , "Entertainer, singer or dancer" , "One entertaining" , "professional dancer?" .)