The most common and most likely answer to this crossword clue is the 4 letter word TAMP
T
A
M
P
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The straight part
We know that "Pat down" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pat down = tamp.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 TAMP mean?
TAMP verb- (blasting) To plug up with clay, earth, dry sand, sod, or other material, as a hole bored in a rock.
- To drive in or pack down by frequent gentle strokes
- To reduce the intensity of.