The most common and most likely answer to this crossword clue is the 3 letter word HEY
I've seen this crossword clue in The Times
H
E
Y
More clues leading to the result HEY
Buddy explains!

The straight part
We know that "call for attention" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case call for attention = hey.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 HEY mean?
HEY interjection- An exclamation to get attention.
- A protest or reprimand.
- An expression of surprise.
- An informal greeting, similar to hi.
- A request for repetition or explanation; an expression of confusion.
- A meaningless beat marker or extra, filler syllable in song lyrics.
- (country dancing) A choreographic figure in which three or more dancers weave between one another, passing by left and right shoulder alternately.
- The name of the fifth letter of many Semitic alphabets (Phoenician, Aramaic, Hebrew, Syriac, Arabic and others).
- The name of the first letter of the Old South Arabian abjad.