The most common and most likely answer to this crossword clue is the 10 letter word IRRIGATION
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More clues leading to the result IRRIGATION
Buddy explains!

The straight part
We know that "Supplying water to crop" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case supplying water to crop = irrigation.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 IRRIGATION mean?
IRRIGATION noun- The act or process of irrigating, or the state of being irrigated; especially, the operation of causing water to flow over lands, for nourishing plants.