The most common and most likely answer to this crossword clue is the 3 plus 3 plus 4 letter word NIP AND TUCK
I've seen this crossword clue in The Daily Telegraph
N
I
P
A
N
D
T
U
C
K
More clues leading to the result NIP AND TUCK
Buddy explains!
The straight part
We know that "Cosmetic surgery/inconclusive as to outcome" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cosmetic surgery/inconclusive as to outcome = nip and tuck.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.