Live in the dearest part (3)
I believe the answer is:
are
'live' is the definition.
(both can mean exist)
'in the dearest part' is the wordplay.
'in' indicates a hidden word.
'ARE' is hidden within 'dearest part'.
(Other definitions for are that I've seen before include "Exist; square measure" , "(They/you/we) exist" , "(We/they/you) exist" , "Is, in the plural" , "(We/you/they) exist" .)