She's precise about one point, relatively speaking (5)
I believe the answer is:
niece
'relatively speaking' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'she's precise about one point' is the wordplay.
'she's precise' becomes 'nice' (I can't justify this - if you can you should believe this answer much more).
'about' indicates putting letters inside.
'one point' becomes 'e' (compass point).
'nice' going around 'e' is 'NIECE'.
Can you help me to learn more?
(Other definitions for niece that I've seen before include "member of different generation" , "A younger female relative" , "One of the family" , "A sibling's daughter" , "Young female relative" .)