Start to blanche more nuts without opening heated container (7)
I believe the answer is:
brazier
'heated container' is the definition.
(a brazier is a portable heater)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for brazier that I've seen before include "Metal container for burning coal or charcoal; warms the watchman" , "Container for lighted coals" , "Outdoor burner" , "Portable container for hot coals" , "Portable coal fire" .)