Uncovers bum note playing something with a bit of sparkle (9)
I believe the answer is:
moonstone
'sparkle' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'uncovers bum note playing something with a bit' is the wordplay.
I cannot quite see how this works, but
an anagram of 'note' is 'tone' which is within the answer.
'playing' could be 'on' (on can mean playing or performing) and 'on' is found in the answer.
'bit' could be 'o' (resembles 0, a binary digit or bit) and 'o' is present in the answer.
The remaining letters 'ms' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'of' acts as a link.
Can you help me to learn more?
(Other definitions for moonstone that I've seen before include "something shiny" , "feldspar" , "Semi-precious gem described in monotones" .)