Word from sister about love (4)
I believe the answer is:
noun
'word' is the definition.
(noun is a kind of word)
'sister about love' is the wordplay.
'sister' becomes 'nun' (I've seen this before).
'about' is an insertion indicator.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'nun' going around 'o' is 'NOUN'.
'from' is the link.
(Other definitions for noun that I've seen before include "Word that refers to a person, place or thing" , "Person, place, thing, state or quality?" , "Word referring to person, place or thing" , "Category of word" , "Type of word" .)