The most common and most likely answer to this crossword clue is the 2 plus 3 plus 4 plus 6 letter word IN THE SAME BREATH
I've seen this crossword clue in The Sunday Telegraph
I
N
T
H
E
S
A
M
E
B
R
E
A
T
H
More clues leading to the result IN THE SAME BREATH
- Sharing soapy water on getting into it together?
- Like two events coming together in a moment of inspiration?
- Simultaneously hint beer has mate reeling
- Together, needing no further inspiration?
- Where oxygen and nitrogen are inhaled, coincidentally
- When both lungs are filled, coincidentally
- Popular article on Mrs Cameron, one’s ultimate inspiration all together
- Exploding methane heats rib simultaneously
Buddy explains!

The straight part
We know that "Together" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case together = in the same breath.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.