The most common and most likely answer to this crossword clue is the 5 letter word SCARP
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More clues leading to the result SCARP
Buddy explains!

The straight part
We know that "slope" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case slope = scarp.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 SCARP mean?
SCARP noun- The steep artificial slope below a fort's parapet
- A cliff at the edge of a plateau or ridge caused by erosion or faulting; the steeper side of an escarpment
- (earth science) to cut, scrape, erode, or otherwise make into a scarp or escarpment