The most common and most likely answer to this crossword clue is the 2 plus 5 letter word LA SCALA
L
A
S
C
A
L
A
More clues leading to the result LA SCALA
- Notes about Tosca not getting to Milan’s opera house
- Finals put aside, girl is permitted to meet boy in Italian theatre
- Reinterpretation of Callas by a famous opera house
- What’s arranged finale for Maria Callas?
- Falstaff, maybe, here left drinkers’ association imbibing special calories
- The French, extremely sycophantic, like opera house
- great operatic scene
- Here’s some wordless singing involving soprano, contralto and alto?
- Villain has removed hat entering Los Angeles theatre
- Where one could be captivated by Callas possibly
Buddy explains!

The straight part
We know that "theatre" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case theatre = la scala.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.