The most common and most likely answer to this crossword clue is the 4 letter word PATS
P
A
T
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More clues leading to the result PATS
Buddy explains!

The straight part
We know that "slaps" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case slaps = pats.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 PATS mean?
PATS noun- The sound of a light slap or tap with a soft flat object, especially of a footstep
- A light tap or slap, especially with the hands
- A flattish lump of soft matter, especially butter or dung.
- To (gently) tap the flat of one's hand on a person or thing.
- To hit lightly and repeatedly with the flat of the hand to make smooth or flat
- To stroke or fondle (an animal).
- To gently rain.
- Patent.
- Pattern.