Little creatures are found in such groups (5)
I believe the answer is:
sects
'such groups' is the definition.
'sects' can be an answer for 'groups' (I've seen this in another clue). I'm not sure about the 'such' bit.
'little creatures are found in' is the wordplay.
'little' says to take the initial letters.
'are found' becomes 'sets' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in' indicates putting letters inside.
The first letter of 'creatures' is 'c'.
'c' put inside 'sets' is 'SECTS'.
Can you help me to learn more?
(Other definitions for sects that I've seen before include "Religious factions" , "Groups of people with divergent religious beliefs" , "Dissenting cliques" , "Orders" , "Groups of people with unconventional religious beliefs" .)