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

The straight part
We know that "Gum" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case gum = paste.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 PASTE mean?
PASTE noun- A soft moist mixture, in particular:
- A substance that behaves as a solid until a sufficiently large load or stress is applied, at which point it flows like a fluid
- A hard lead-containing glass, or an artificial gemstone made from this glass.
- Pasta.
- The mineral substance in which other minerals are embedded.
- To stick with paste; to cause to adhere by or as if by paste.
- To insert a piece of media (e.g. text, picture, audio, video) previously copied or cut from somewhere else.
- To strike or beat someone or something.
- To defeat decisively or by a large margin.