An enchanter uses these periods (6)
I believe the answer is:
spells
'these periods' is the definition.
(spell is a kind of period)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for spells that I've seen before include "Short periods of time" , "Periods of times or witche's curses" , "seasons" , "Witches cast them" , "Magic influences" .)