One old-fashioned star (4)
I believe the answer is:
idol
'star' is the definition.
(idol is a kind of star)
'one old-fashioned' is the wordplay.
'one' becomes 'i' (Roman numeral**).
'fashioned' indicates an anagram.
'old' anagrammed gives 'dol'.
'i'+'dol'='IDOL'
(Other definitions for idol that I've seen before include "Film star" , "Much-loved actor" , "Object of false worship" , "Figure worshipped - sounds like someone in 7 8" , "As before, fake" .)