The most common and most likely answer to this crossword clue is the 2 plus 2 plus 2 letter word LA DI DA
I've seen this crossword clue in The Daily Telegraph
L
A
D
I
D
A
More clues leading to the result LA DI DA
Buddy explains!
The straight part
We know that "trying to be posh" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case trying to be posh = la di da.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 LA DI DA mean?
LA DI DA adjective- Of or from the upper class of society.
- Affecting upper-class or superior airs.
- (mildly) Expression of disdain for pretension or haughtiness.
- Not a care in the world (used in a sing-song voice, for childhood rhymes)