Is in manuscript form for a teacher (4)
I believe the answer is:
miss
'teacher' is the definition.
(I've seen this before)
'is in manuscript' is the wordplay.
'in' indicates putting letters inside.
'manuscript' becomes 'ms' ('ms' can be a synonym of 'manuscript').
'is' inserted inside 'ms' is 'MISS'.
'form for a' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for miss that I've seen before include "Fail to hit (something)" , "Agatha Christie's detective" , "Fail to hear" , "Fail; long for" , "Girl or unmarried woman" .)