The most common and most likely answer to this crossword clue is the 4 letter word RICK
I've seen this crossword clue in The Sunday Telegraph
R
I
C
K
More clues leading to the result RICK
Buddy explains!
The straight part
We know that "Pile of hay" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case pile of hay = rick.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 RICK mean?
RICK noun- Straw, hay etc. stored in a stack for winter fodder, commonly protected with thatch.
- A stack of wood, especially cut to a regular length; also used as a measure of wood, typically four by eight feet.
- To heap up (hay, etc.) in ricks.
- To slightly sprain or strain the neck, back, ankle etc.
- A brand new (naive) boot camp inductee.