Type of group that might get under one's skin? (8)
I believe the answer is:
splinter
I believe this clue is a double definition.
'type of group' is the first definition.
(splinter group)
'that might get under one's skin?' is the second definition.
(Other definitions for splinter that I've seen before include "Thin sliver of wood" , "Sharp wood fragment, painful in flesh" , "Thin sharp piece of wood or glass" , "Needle-like piece of wood" , "Thin needle-like piece" .)