The sweet boy took us back first (6)
I believe the answer is:
sugary
'the sweet' is the definition.
(I've seen this before)
'took us back first' is the wordplay.
'took' becomes 'gary' (I can't explain this - if you can you should give a lot more credence to this answer).
'back' says the letters should be written backwards.
'first' means one lot of letters go next to another.
'us' backwards is 'su'.
'gary' after 'su' is 'SUGARY'.
'boy' is the link.
Can you help me to learn more?
(Other definitions for sugary that I've seen before include "Sweet, syrupy" , "Over-sentimental" , "Excessively sweet or saccharine" , "Sweet, perhaps too much so" , "Excessively sentimental" .)