Pop music centre regenerated Mary's classic sitcom (4,4)
I believe the answer is:
dads army
'classic sitcom' is the definition.
(classic British sitcom)
'pop music centre regenerated mary's' is the wordplay.
'pop' becomes 'dad' (both can mean one's father).
'centre' indicates the central letters.
'regenerated' indicates anagramming the letters.
The middle of 'music' is 's'.
'mary' anagrammed gives 'army'.
'dad'+'s'+'army'='DADS ARMY'
(Other definitions for dads army that I've seen before include "British sitcom featuring the Home Guard" , "Evergreen TV comedy" , "Show" , "TV programme" .)