The most common and most likely answer to this crossword clue is the 16 letter word LADYÂ OFÂ THEÂ LAMP
I've seen this crossword clue in The Guardian
L
A
D
Y
Â
O
F
Â
T
H
E
Â
L
A
M
P
Buddy explains!
The straight part
We know that "Nurse" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case nurse = lady of the lamp.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.