Scoundrels held up this celebrity (4)
I believe the answer is:
star
'this celebrity' is the definition.
(I've seen this before)
'scoundrels held up' is the wordplay.
'scoundrels' becomes 'rats' (rat can mean a scoundrel or dishonourable person).
'held up' says the letters should be written in reverse.
'rats' in reverse letter order is 'STAR'.
(Other definitions for star that I've seen before include "A heavenly body or film favourite" , "Eg, Betelgeuse" , "virtuoso" , "Bright" , "Outstanding entertainer" .)