The most common and most likely answer to this crossword clue is the 3 plus 3 letter word ALT KEY
I've seen this crossword clue in Independent
A
L
T
K
E
Y
More clues leading to the result ALT KEY
Buddy explains!
The straight part
We know that "component of PC’s interface (keyboard)" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case component of pc’s interface (keyboard) = alt key.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.