Orchestral passage — dear me, it's over! (5)
I believe the answer is:
tutti
'orchestral passage' is the definition.
(I've seen this in another clue)
'dear me it's over' is the wordplay.
'dear me' becomes 'tut' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'over' says the letters should be written in reverse.
'it' back-to-front is 'ti'.
'tut'+'ti'='TUTTI'
Can you help me to learn more?
(Other definitions for tutti that I've seen before include "when everyone plays" , "(Musically) performed by all instruments" , "Everybody (mus.)" , "All (stage direction)" , "Instruction for all orchestral instruments to play together" .)