The most common and most likely answer to this crossword clue is the 9 letter word DALLIANCE
I've seen this crossword clue in The Daily Telegraph
D
A
L
L
I
A
N
C
E
More clues leading to the result DALLIANCE
- Affair and, ultimately, marriage?
- Everything I wanted in social flirting
- Kinship behind daughter’s flirting
- Virtually exhausted in social function, a waste of time
- Fling ending in bed with coupling
- Flirtation beginning to damage partnership
- Flirting daughter joins friendly group
- Flirtation shown by every setter during smooch
- Flirting gets Penny a relationship
- Daughter’s marriage regarded as a casual affair!
Buddy explains!
The straight part
We know that "Brief affair" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case brief affair = dalliance.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 DALLIANCE mean?
DALLIANCE noun- Playful flirtation; amorous play.
- A wasting of time in idleness or trifles.
- A sexual relationship, not serious but often illicit.