The most common and most likely answer to this crossword clue is the 5 letter word ETTLE
E
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The straight part
We know that "In Ayr aim" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case in ayr aim = ettle.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 ETTLE mean?
ETTLE noun- Intention; intent; aim.
- To aim; purpose; intend; attempt; try.
- To expect; reckon; count on.
- To take aim.
- To make attempt.
- To direct one's course.
- To aspire; be ambitious.
- To earn.