Doctor takes certain pains, refuses a box of goodies (8,5)
I believe the answer is:
treasure chest
'box of goodies' is the definition.
'treasure chest' can be an answer for 'box' (treasure chest is a kind of box). I'm not sure about the 'of goodies' bit.
'doctor takes certain pains refuses a' is the wordplay.
I cannot really see how this works, but
'certain' could be 'sure' (similar in meaning) and 'sure' is found in the answer.
'pains' could be 'chest' (chest pain is a kind of pain) and 'chest' is present in the answer.
'a' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for treasure chest that I've seen before include "Hoard of valuables" , "Precious box" , "Container of much wealth" , "Box of wealth" , "Box for valuables" .)