Princess lives with elderly European (6)
I believe the answer is:
isolde
'princess' is the definition.
(I've seen this before)
'lives with elderly european' is the wordplay.
'lives' becomes 'is' ('be' can be a synonym of 'live').
'with' says to put letters next to each other.
'elderly' becomes 'old' ('old' can be similar in meaning to 'elderly').
'european' becomes 'e' (abbreviation e.g. EU).
'is'+'old'+'e'='ISOLDE'
(Other definitions for isolde that I've seen before include "Arthurian queen" , "for Tristram" , "Tristan and ... (Wagner opera)" , "Wagnerian heroine" , "princess of legend" .)