Groups of reps? (4)
I believe the answer is:
sets
'groups of reps?' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sets that I've seen before include "Places" , "Scenery etc. of 11 across productions" , "Solidifies" , "Classes" , "Scenery etc. of dramatic productions" .)