Grub of a popular variety (5)
I believe the answer is:
larva
'grub' is the definition.
(I know that grub can be written as larva)
'of a popular variety' is the wordplay.
'of' indicates the answer is hidden within the clue.
'LARVA' can be found hidden inside 'popular variety'.
(Other definitions for larva that I've seen before include "Maggots" , "Grub, caterpillar stage" , "Caterpillar, for example" , "Caterpillar perhaps" , "Insect just out of egg" .)