The most common and most likely answer to this crossword clue is the 9 letter word CONCORDAT
C
O
N
C
O
R
D
A
T
More clues leading to the result CONCORDAT
- Doctor can upset agreement
- State capital in New England, a leader in trade pact
- Study cable leading to a tense agreement
- Agreement doctor can set out
- Agreement producing new line in outerwear
- Agreement about material getting snagged by puss
- A leader in Turkey supporting deception over line in pact
- Devious doctor can make deal
- A short time after US state capital makes a pact
- Doctor can corrupt official agreement
Buddy explains!

The straight part
We know that "deal" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case deal = concordat.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.
What does CONCORDAT mean?
CONCORDAT noun- A formal agreement between two parties, especially between a church and a state; specifically, an agreement between the Pope and a government.