To sum up, I see a novice in a show (7)
I believe the answer is:
musical
'a show' is the definition.
(I know that show can be written as musical)
'to sum up i see a novice in' is the wordplay.
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'see a novice in' becomes 'cal' (I can't justify this - if you can you should give a lot more credence to this answer).
'sum' reversed gives 'mus'.
'mus'+'i'+'cal'='MUSICAL'
Can you help me to learn more?
(Other definitions for musical that I've seen before include "Cats maybe" , "Song and dance show" , "Drama where songs are more important than plot" , "Show, with numbers" , "Oliver perhaps" .)