Downbeat artist's gripped by good southern country music
I believe the answer is:
bluegrass
'country music' is the definition.
(I've seen this before)
'downbeat artist's gripped by good southern' is the wordplay.
'downbeat' becomes 'blue' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'artist's' becomes 'ras' (Royal Academician's abbreviation).
'gripped by' is an insertion indicator.
'good' becomes 'g' (abbreviation).
'southern' becomes 's' (abbreviation).
'g'+'s'='gs'
'ras' put inside 'gs' is 'grass'.
'blue'+'grass'='BLUEGRASS'
Can you help me to learn more?
(Other definitions for bluegrass that I've seen before include "nickname of US State" , "A type of country music" , "Style of country music from Kentucky" , "Style of US country music" , "Kind of country music" .)