The most common and most likely answer to this crossword clue is the 6 letter word SOCIAL
I've seen this crossword clue in The Times
S
O
C
I
A
L
More clues leading to the result SOCIAL
- Gregarious solicitor collaring security outfit
- Left-winger is distraught, ultimately leaving party
- Party, only not the right wing, probed by one in Central America
- Cola is served up in informal gathering
- Thus American spies left an informal gathering
- I also worried about Conservative Party
- Willing to mix upper-crust elements to obtain firm backing
- Group that's very large including agents abroad
- Friendly note on beauty treatment has lowered tone
- Cola is ordered for a party
Buddy explains!

The straight part
We know that "Party" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case party = social.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 SOCIAL mean?
SOCIAL noun- A festive gathering to foster introductions.
- A dance held to raise money for a couple to be married.
- A dinner dance event, usually held annually by a company or sporting club.
- A social media account.
- Being extroverted or outgoing.
- Of or relating to society.
- Relating to social media or social networks.
- Relating to a nation's allies.
- Cooperating or growing in groups.
- Interactive forms of media that allow users to interact with and publish to each other, generally by means of the Internet.
- A system whereby the state either through general or specific taxation provides various benefits to help ensure the wellbeing of its citizens.
- Those benefits paid under such a system.
- A specific such social benefit providing income in retirement or disability.
- A nine-digit number issued to citizens, permanent residents, and temporary (working) residents under section 205(c)(2) of the Social Security Act, codified as 42 U.S.C. ยง 405(c)(2). The number is issued to an individual by the Social Security Administration. Its primary purpose is to track individuals for taxation purposes. Abbreviated as SSN. In recent years the SSN has become a de facto national identification number.
- A corresponding number in other countries.
- The study of history, geography, civics, sociology, economics, and other social-science subjects, especially in primary and secondary school.