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

The straight part
We know that "Infatuation" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case infatuation = crush.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 CRUSH mean?
CRUSH noun- A violent collision or compression; a crash; destruction; ruin.
- Violent pressure, as of a moving crowd.
- A crowd that produces uncomfortable pressure.
- A violent crowding.
- A crowd control barrier.
- A drink made by squeezing the juice out of fruit.
- An infatuation with somebody one is not dating.
- A standing stock or cage with movable sides used to restrain livestock for safe handling.
- A party or festive function.
- The process of crushing cane to remove the raw sugar, or the season when this process takes place.
- To press between two hard objects; to squeeze so as to alter the natural shape or integrity of it, or to force together into a mass.
- To reduce to fine particles by pounding or grinding
- To overwhelm by pressure or weight.
- To oppress or grievously burden.
- To overcome completely; to subdue totally.
- To be or become broken down or in, or pressed into a smaller compass, by external weight or force
- To feel infatuation or unrequited love.
- To give a compressed or foreshortened appearance to.