Vocalist keeping extremely popular type of spaniel (8)
I believe the answer is:
springer
'type of spaniel' is the definition.
(I've seen this before)
'vocalist keeping extremely popular' is the wordplay.
'vocalist' becomes 'singer' ('singer' can be a synonym of 'vocalist'**).
'keeping' indicates putting letters inside.
'extremely' says to hollow out the word (remove centre letters).
'popular' with its centre removed is 'pr'.
'singer' going around 'pr' is 'SPRINGER'.
(Other definitions for springer that I've seen before include "Shown [AT CRUFTS]" , "Type of spaniel" , "A spaniel; stone in arch" , "A bounder" , "Kind of spaniel" .)