Detestable group one demonstrating perhaps (6)
I believe the answer is:
shower
'detestable group' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for shower that I've seen before include "that's revealing?" , "Plumbing fixture and brief period of precipitation" , "bathroom fitment" , "Fall of rain; slack people (slang)" , "Something depicting" .)