Do not change income, essentially, for backing groups (6)
I believe the answer is:
octets
'do not change income essentially for backing groups' is the definition.
I can't tell whether this defines the answer.
'change income essentially for backing groups' is the wordplay.
'change' is an anagram indicator.
'essentially' says to take the centre.
'for backing' says the letters should be written in reverse.
'groups' becomes 'stet' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
The middle of 'income' is 'co'.
'stet' back-to-front is 'tets'.
'co' anagrammed gives 'oc'.
'oc'+'tets'='OCTETS'
Can you help me to learn more?
(Other definitions for octets that I've seen before include "Groups of eight, often singers" , "Sets of eight" , "groups of eight, say singers" , "Groups of eight peformers" .)