Sugary liquid comprising nitrogen and trace elements (6)
I believe the answer is:
nectar
'sugary liquid' is the definition.
(nectar is a sweet liquid)
'nitrogen and trace elements' is the wordplay.
'nitrogen' becomes 'N' (N is the chemical symbol for nitrogen).
'and' means one lot of letters go next to another.
'elements' is an anagram indicator (the letters or elements of the word in a new order).
'trace' anagrammed gives 'ectar'.
'n'+'ectar'='NECTAR'
'comprising' is the link.
(Other definitions for nectar that I've seen before include "That's sweet" , "sweet stuff" , "Ambrosia" , "Source of honey" , "From which 18dn is made" .)