Teachers having no head make bloomers (6)
I believe the answer is:
asters
'teachers having no head make bloomers' is the definition.
I can't judge whether this defines the answer.
'teachers having no head' is the wordplay.
'teachers' becomes 'masters' (old word for teachers).
'having no head' means to remove the first letter (I've seen 'has no head' mean this).
'masters' with its initial letter taken off is 'ASTERS'.
Can you help me to learn more?
(Other definitions for asters that I've seen before include "A rest's a change from flowers" , "Stares at bright flowers" , "Otherwise known as Michaelmas daisies" , "Christmas daisies" , "Stares oddly at the flowers" .)