Sign that is featured in classical art (5)
I believe the answer is:
aries
'sign' is the definition.
(star sign)
'that is featured in classical art' is the wordplay.
'that is' becomes 'ie' (synonyms).
'featured in' indicates putting letters inside.
'classical art' becomes 'ars' ('art' in Latin).
'ie' put into 'ars' is 'ARIES'.
(Other definitions for aries that I've seen before include "A sign from Heaven" , "Zodiacal sign also known as the Ram" , "First sign of the zodiac" , "Philip -, English poet" , "Stars" .)