The most common and most likely answer to this crossword clue is the 5 letter word MIXER
M
I
X
E
R
Buddy explains!
The straight part
We know that "Socialiser" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case socialiser = mixer.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 MIXER mean?
MIXER noun- One who, or a device that, mixes or merges things together.
- One who mixes or socializes.
- A machine outfitted with (typically blunt) blades with which it mixes or beats ingredients in a bowl below.
- A non-alcoholic drink (such as lemonade, Coca-Cola or fruit juice) that is added to spirits to make cocktails.
- A mixing console.
- A dance or other social event meant to foster new acquaintances, as at the beginning of a school year.
- Any of various social dances involving frequent changes of partners.
- A device for combining hot and cold water before it emerges from a single spout or shower head.
- A nonlinear electrical circuit that creates new frequencies from two signals applied to it.