She lives in Los Angeles (4)
I believe the answer is:
lisa
'she' is the definition.
'lives in los angeles' is the wordplay.
'lives' becomes 'is' ('be' can be a synonym of 'live').
'in' means one lot of letters goes inside another.
'los angeles' becomes 'LA' (abbreviation).
'is' placed within 'la' is 'LISA'.
(Other definitions for lisa that I've seen before include "Most intelligent of Marge Simpson's children" , "Leonardo da Vinci painted the 'Mona ....'" , "Mona . . . ., famous painting by Leonardo da Vinci" , "Mona ..., also called La Gioconda" , "Girl" .)