Seen in a group, a teacher or the head (4)
I believe the answer is:
pate
'the head' is the definition.
(humorous term for the head)
'seen in a group a teacher' is the wordplay.
'seen in' says the answer is hidden in the clue.
'PATE' can be found hidden inside 'a group a teacher'.
'or' acts as a link.
(Other definitions for pate that I've seen before include "Top of one's head" , "Head, perhaps bald" , "Meat paste, perhaps de foie gras" , "Tape for a head" , "Head - meat spread" .)