A group in a social level in the tape holder (8)
I believe the answer is:
cassette
'the tape holder' is the definition.
(I've seen this before)
'a group in a social level' is the wordplay.
'a group' becomes 'set' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in' means one lot of letters goes inside another.
'a social level' becomes 'caste' (I've seen this in another clue).
'set' inserted inside 'caste' is 'CASSETTE'.
'in' is the link.
Can you help me to learn more?
(Other definitions for cassette that I've seen before include "sealed plastic container" , "recording device" , "Audio tape holder" , "Source of music" , "Test case (anag.)" .)