Weed end of patch, near tree (4)
I believe the answer is:
hash
'weed' is the definition.
(hash is a kind of weed)
'end of patch near tree' is the wordplay.
'end of' indicates one should take the final letters.
'near' means one lot of letters go next to another.
'tree' becomes 'ash' (ash is a kind of tree**).
The last letter of 'patch' is 'h'.
'h'+'ash'='HASH'
(Other definitions for hash that I've seen before include "Recycled food" , "Error" , "reheated meat and vegetables" , "Stew - botched job" , "number provided by American" .)