The most common and most likely answer to this crossword clue is the 3 plus 11 letter word HIP REPLACEMENT
I've seen this crossword clue in The Guardian
H
I
P
R
E
P
L
A
C
E
M
E
N
T
Buddy explains!
The straight part
We know that "theatre work" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case theatre work = hip replacement.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.