Really appreciate artist during god’s festival (5,4)
I believe the answer is:
mardi gras
'festival' is the definition.
(Mardi Gras is an example)
'really appreciate artist during god's' is the wordplay.
'really appreciate' becomes 'dig' (to dig something is to appreciate it).
'artist' becomes 'RA' (Royal Academician, member of Royal Academy of Arts).
'during' indicates putting letters inside.
'god' becomes 'mars' (Mars is an example).
'dig'+'ra'='digra'
'digra' put inside 'mars' is 'MARDI GRAS'.
(Other definitions for mardi gras that I've seen before include "Revelry celebrating Shrove Tuesday" , "Shrove Tuesday celebration" , "pre-Lent festival" , "Time for carnival" , "Carnival (day)" .)