Pop star back in country garden (7)
I believe the answer is:
rockery
'garden' is the definition.
(rockery is a kind of garden)
'pop star back in country' is the wordplay.
'pop star' becomes 'rocker' (a rock musician).
'back in' indicates one should take the final letters (the 'back' of the word).
The last letter of 'country' is 'y'.
'rocker'+'y'='ROCKERY'
(Other definitions for rockery that I've seen before include "Garden feature with alpines" , "Part of garden" , "Garden alpine area" .)