It's up to an academician to provide something topping! (5)
I believe the answer is:
tiara
'provide something topping' is the definition.
I can't judge whether this defines the answer.
'it's up to an academician' is the wordplay.
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'to an academician' becomes 'ara'.
'it' backwards is 'ti'.
'ti'+'ara'='TIARA'
'to' is the link.
Can you help me to learn more?
(Other definitions for tiara that I've seen before include "expensive headwear" , "Jewelled head ornament" , "Decorative headband" , "it goes to one's head!" , "Great delight" .)