The most common and most likely answer to this crossword clue is the 8 plus 2 letter word STANDING BY
I've seen this crossword clue in The Guardian
S
T
A
N
D
I
N
G
B
Y
Buddy explains!

The straight part
We know that "Liable to be called" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case liable to be called = standing by.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.