Animal sound in south, pleasing to the ear (6)
I believe the answer is:
smooth
'pleasing to the ear' is the definition.
(as in smooth music)
'animal sound in south' is the wordplay.
'animal sound' becomes 'moo' (cows go moo).
'in' indicates putting letters inside.
'south' becomes 'sth' (abbreviation for south).
'moo' inserted inside 'sth' is 'SMOOTH'.
(Other definitions for smooth that I've seen before include "Calm" , "Do ironing" , "Not uneven or rough" , "Regular - without problems" , "Glossy" .)