The most common and most likely answer to this crossword clue is the 6 plus 7 letter word SOCIAL CLIMBER
I've seen this crossword clue in The Daily Telegraph
S
O
C
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A
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C
L
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M
B
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More clues leading to the result SOCIAL CLIMBER
- Liberal's comic — phoney person who leaves the less well-off behind?
- Party attended by mountaineer, one seeking status?
- Mountaineer supporting party — an uppish type?
- An Ivy League wannabe?
- Party clothes initially paraded by agile upwardly mobile member of the Ant Hill Mob?
- One wants to join another class and do something in the garden
- Conservative in party flexible — one out to impress superiors
- Funny liberal comic’s one getting on in the world
- Status seeker in party gets agile, snorting cocaine
Buddy explains!
The straight part
We know that "One wants to join another class" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case one wants to join another class = social climber.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.