Crossword Genius

Make a mess at the top of Hazelwood tree (4)

Ross

I believe the answer is:

hash

I'm a little stuck... Click here to teach me more about this clue!

'make a mess' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

'at the top of hazelwood tree' is the wordplay.
'at' means one lot of letters go next to another.
'the top of' says to take the initial letters.
'tree' becomes 'ash' (ash tree is a kind of tree**).
The first letter of 'hazelwood' is 'h'.
'h'+'ash' is 'HASH'.

Can you help me to learn more?

(Other definitions for hash that I've seen before include "Mess; meat/potato dish" , "Dish of diced meat etc - cannabis (slang)" , "Chopped meat mixed with potatoes and browned" , "Recycled food" , "meat and potato dish" .)

I've seen this clue in the Irish Times.
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