Oily substance from tree put in ground with nitrogen (10)
I believe the answer is:
turpentine
'oily substance' is the definition.
'turpentine' can be an answer for 'substance' (turpentine is a kind of substance). I am not certain of the 'oily' bit.
'tree put in ground with nitrogen' is the wordplay.
'ground with' indicates an anagram ('grind' the letters into a new form).
'nitrogen' becomes 'N' (N is the chemical symbol for nitrogen).
'tree'+'put'+'in'='treeputin'
'treeputin' anagrammed with 'n' makes 'TURPENTINE'.
'from' acts as a link.
Can you help me to learn more?
(Other definitions for turpentine that I've seen before include "Oil used in mixing paints" , "Solvent" , "Thick, oily resin used as paint thinner" , "artist's stuff" , "Oil used in varnishes" .)