Hesitation to follow up formal introduction (6)
I believe the answer is:
primer
'introduction' is the definition.
(I've seen this before)
'hesitation to follow up formal' is the wordplay.
I cannot quite understand how this works, but
'hesitation' could be 'er' (sound used when hesitating) and 'er' is found in the answer.
'formal' could be 'prim' (I've seen this in another clue) and 'prim' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for primer that I've seen before include "School textbook" , "Sealant coat" , "Basic teaching book" , "First school book" , "Initial coat of paint" .)