The most common and most likely answer to this crossword clue is the 7 letter word THWACKS
I've seen this crossword clue in Independent
T
H
W
A
C
K
S
More clues leading to the result THWACKS
- Hits nails — hard wood initially to penetrate
- Hits to hear at first by Ruby on the radio
- . Strikes hit workers initially involved in courses
- Changes course to take in principally how wind blows
- Hot wife splits nails and hits out
- Possibly what half-bricks get to make them so?
- New watch, neckties often seen in boxes
Buddy explains!

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 THWACKS mean?
THWACKS noun- The act of thwacking; a strike or blow, especially with a flat implement.
- A heavy slapping sound.
- To hit with a flat implement.
- To beat.
- To fill to overflow.