heat, radiate heat, broil, cauterize
焮 centers on intense heat applied to something: radiating heat, broiling, or using heat to cauterize and seal a wound.
焮 combines 火 (fire) with 欣, which likely contributes the sound キン and may carry a sense of strong or intense action, together suggesting intense heat or cauterizing.
Fire 火 on the left and 欣 on the right: picture a blazing fire radiating heat so intensely that it can broil food or cauterize a wound.
For キン, imagine a hot kiln radiating heat: kiln -> キン, and the fire 火 makes the kiln broil and cauterize.