Musical production taking a long time? (5)

I believe the answer is:

opera

I'm a little stuck... Click here to teach me more about this clue!

'musical production' is the definition.
(I've seen this in another clue)

'a long time?' is the wordplay.
'a long' becomes 'op' (I can't explain this - if you can you should give a lot more credence to this answer).
'time?' becomes 'era' (era is a kind of time).
'op'+'era'='OPERA'

'taking' acts as a link.

Can you help me to learn more?

(Other definitions for opera that I've seen before include "Stage entertainment" , "Carmen, for example" , "Aida, for example" , "Music and drama production" , "eg 'Aida'" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.