Grub of regular variety (5)
I believe the answer is:
larva
'grub' is the definition.
(thesaurus)
'of regular variety' is the wordplay.
'of' indicates the answer is hidden within the clue.
'LARVA' can be found hidden inside 'regular variety'.
(Other definitions for larva that I've seen before include "Woodworm" , "Immature life form" , "Insect in the first post-egg stage of its life" , "Insect's immature form" , "Caterpillar, for example" .)