Not thinking about what constitutes make-over (6)
I believe the answer is:
rehash
'not thinking' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'what constitutes make-over' is the wordplay.
'what' becomes 'eh' (I've seen this in other clues).
'constitutes make' becomes 'rash' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'over' is an insertion indicator.
'eh' placed within 'rash' is 'REHASH'.
'about' acts as a link.
Can you help me to learn more?
(Other definitions for rehash that I've seen before include "Use old material in a new form" , "Use again (changing little)" , "Put old material into new form without much change" , "new disposition" , "Re-use old material with little or no change" .)