Serious listener with cosy home (7)
I believe the answer is:
earnest
'serious' is the definition.
(similar in meaning)
'listener with cosy home' is the wordplay.
'listener' becomes 'ear' (body part which hears or listens).
'with' says to put letters next to each other.
'cosy home' becomes 'nest'.
'ear'+'nest'='EARNEST'
(Other definitions for earnest that I've seen before include "showing seriousness" , "Serious or heartfelt" , "Eastern (anag.)" , "Serious in intention" , "Serious - advance" .)