They're used when retiring teacher's drinking punch (8)
I believe the answer is:
bedsocks
'they're used when retiring' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'teacher's drinking punch' is the wordplay.
'teacher's' becomes 'BEd's' (Bachelor of Education).
'drinking' is an insertion indicator (inserted letters are consumed or drunk).
'punch' becomes 'sock' (I've seen this in another clue).
'beds' placed around 'sock' is 'BEDSOCKS'.
Can you help me to learn more?
(Other definitions for bedsocks that I've seen before include "Night-time footwear" , "Nighttime attire" , "Night attire" , "Garments worn when asleep" , "Night wear for feet" .)