Make changes to steps at back of class (5)
I believe the answer is:
rejig
'make changes to steps' is the definition.
I can't judge whether this defines the answer.
'at back of class' is the wordplay.
'at' means one lot of letters go next to another.
'back of' becomes 'jig' (I can't justify this - if you can you should give a lot more credence to this answer).
'class' becomes 'RE' (Religious Education, school subject).
'jig' after 're' is 'REJIG'.
Can you help me to learn more?
(Other definitions for rejig that I've seen before include "Equip again" , "Alter" , "Re-equip for new kind of work" , "Manipulate" , "Arrange another way" .)