Appeared on very big special appearances (6)
I believe the answer is:
cameos
'special appearances' is the definition.
(I've seen this in another clue)
'appeared on very big' is the wordplay.
'appeared' becomes 'came' (I've seen this in another clue).
'on' says to put letters next to each other.
'very big' becomes 'os' (abbreviation for outsize).
'came'+'os'='CAMEOS'
(Other definitions for cameos that I've seen before include "Came so close to small carvings" , "Small stones carved with raised designs" , "pieces of jewelry" , "Portraits in profile carved in relief" , "Small pieces of stone carved with raised designs" .)