Confectionery is able to empty day (5)
I believe the answer is:
candy
'confectionery' is the definition.
(candy is a kind of confectionery)
'able to empty day' is the wordplay.
'able' becomes 'can'.
'to empty' says to hollow out the word (remove centre letters).
'day' with its middle removed is 'dy'.
'can'+'dy'='CANDY'
'is' is the link.
(Other definitions for candy that I've seen before include "Sugary sweet" , "Crystallised sugar; US sweets" , "Girl's name (diminutive)" , "American sweets" , "Sweet (US)" .)