The most common and most likely answer to this crossword clue is the 11 plus 11 letter word ALL-SINGING ALL-DANCING
A
L
L
-
S
I
N
G
I
N
G
A
L
L
-
D
A
N
C
I
N
G
Buddy explains!
The straight part
We know that "Doing everything" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case doing everything = all-singing all-dancing.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.