Glitter a large deer knocks over (7)
I believe the answer is:
sparkle
'glitter' is the definition.
(I know that glitter can be written as sparkle)
'a large deer knocks over' is the wordplay.
'a large deer' becomes 'elk' (I've seen this before).
'knocks' becomes 'raps' ('rap' can be a synonym of 'knock').
'over' says the letters should be written backwards.
'elk'+'raps'='elkraps'
'elkraps' reversed gives 'SPARKLE'.
(Other definitions for sparkle that I've seen before include "showing wit" , "Flash brightly" , "Be vivacious and witty" , "Shine brightly" , "exhibit vivacity" .)