She upsets Eva in an out-of-the-way way (5)
I believe the answer is:
vesta
'she upsets eva' is the definition.
I can't tell whether this defines the answer.
'in an out-of-the-way way' is the wordplay.
'in' means one lot of letters goes inside another.
'an out-of-the' becomes 'va' (I can't justify this - if you can you should believe this answer much more).
'way' becomes 'e' (Compass direction - East).
'way' becomes 'st' (abbreviation for street).
'e'+'st'='est'
'va' going around 'est' is 'VESTA'.
Can you help me to learn more?
(Other definitions for vesta that I've seen before include "Stave (anag.)" , "Roman goddess; match" , "Hearth goddess; a match" , "Roman goddess of the hearth" , "heavenly body" .)