Star shown up in cello display (4)
I believe the answer is:
idol
'star' is the definition.
(I know that idol is a type of star)
'up in cello display' is the wordplay.
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'in' says the answer is hidden in the clue.
'lodi' is hidden in the letters of 'cello display'.
'lodi' reversed gives 'IDOL'.
'shown' acts as a link.
(Other definitions for idol that I've seen before include "Pop - - (TV)" , "Hero, star" , "Someone much loved" , "Effigy" , "Film star" .)