The most common and most likely answer to this crossword clue is the 3 letter word HIP
I've seen this crossword clue in The Daily Telegraph
H
I
P
Buddy explains!

The straight part
We know that "Youth culture" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case youth culture = hip.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 HIP mean?
HIP noun- The outward-projecting parts of the pelvis and top of the femur and the overlying tissue.
- The inclined external angle formed by the intersection of two sloping roof planes.
- In a bridge truss, the place where an inclined end post meets the top chord.
- (possibly obsolete) A drug addict, especially someone addicted to a narcotic like heroin.
- To use one's hips to bump into someone.
- To throw (one's adversary) over one's hip ("cross-buttock").
- To dislocate or sprain the hip of, to fracture or injure the hip bone of (a quadruped) in such a manner as to produce a permanent depression of that side.
- To make with a hip or hips, as a roof.
- The fruit of a rose.
- To inform, to make knowledgeable.
- Aware, informed, up-to-date, trendy.