Show Sid up at drama (7)
I believe the answer is:
display
'show' is the definition.
(display can mean to show or expose)
'sid up at drama' is the wordplay.
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'at' is a charade indicator (letters next to each other).
'drama' becomes 'play' (synonyms).
'sid' backwards is 'dis'.
'dis'+'play'='DISPLAY'
(Other definitions for display that I've seen before include "Show or arrange" , "Put on show" , "Showcase" , "Show to the public" , "Exhibition" .)