Teacher with a number of gowns perhaps and mortarboards
I believe the answer is:
headgear
'gowns perhaps and mortarboards' is the definition.
I can't judge whether this definition defines the answer.
'teacher with a number' is the wordplay.
'teacher' becomes 'head'.
'with' is a charade indicator (letters next to each other).
'a number' becomes 'gear' (I can't justify this - if you can you should believe this answer much more).
'head'+'gear'='HEADGEAR'
'of' is the link.
Can you help me to learn more?
(Other definitions for headgear that I've seen before include "Balmoral, perhaps" , "Hats, bonnets, caps etc" , "Aged hare? (anagram)" , "Mortarboard < , especially" , "helmet, for instance" .)