Gran, for one, dances to reggae groups (8)
I believe the answer is:
ancestor
'gran for one' is the definition.
'dances to reggae groups' is the wordplay.
'groups' indicates a hidden word (makes a group of the solution).
'ANCESTOR' can be found hidden inside 'dances to reggae'.
(Other definitions for ancestor that I've seen before include "descent comes from one" , "Adam was our first one" , "not being of the modern generation" , "one is up a tree" , "Forefather" .)