Musical instrument in case picked up by versatile ace (7)
I believe the answer is:
celesta
'musical instrument' is the definition.
(celesta is a kind of musical instrument)
'in case picked up by versatile ace' is the wordplay.
I cannot quite understand how this works, but
'ace' could be 'a' and 'a' is found in the answer.
'in case' could be 'lest' (I've seen this in another clue) and 'lest' is found in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for celesta that I've seen before include "Musical instrument" , "Keyboard percussion instrument giving a bell-like sound" , "Play this" , "one giving out notes" , "a bunch of keys?" .)