Chemistry equipment cook ruining cakes has sent briefly in (6,6)
I believe the answer is:
bunsen burner
'chemistry equipment' is the definition.
(Bunsen burners are used in chemistry)
'cook ruining cakes has sent briefly in' is the wordplay.
I cannot really see how this works, but
'cakes' could be 'buns' (cake is a type of bun) and 'buns' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for bunsen burner that I've seen before include "Chemistry lab heater" , "Lab equipment with an adjustable flame" , "Laboratory heat source" , "Item of laboratory equipment" .)