The most common and most likely answer to this crossword clue is the 3 plus 5 plus 6 letter word THE THIRD PERSON
I've seen this crossword clue in Independent
T
H
E
T
H
I
R
D
P
E
R
S
O
N
Buddy explains!
The straight part
We know that "E.g. She" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case e.g. she = the third person.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.