The most common and most likely answer to this crossword clue is the 5 letter word SLUNG
I've seen this crossword clue in The Daily Telegraph
S
L
U
N
G
More clues leading to the result SLUNG
Buddy explains!

The straight part
We know that "Cast" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cast = slung.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 SLUNG mean?
SLUNG verb- To throw with a circular or arcing motion.
- To throw with a sling.
- To pass a rope around (a cask, gun, etc.) preparatory to attaching a hoisting or lowering tackle.
- To sell, peddle, or distribute illicitly (e.g. drugs, sex, etc.).