The writer is taken aback about periodically harsh language (5)
I believe the answer is:
masai
'language' is the definition.
(Masai is an example)
'the writer is taken aback about periodically harsh' is the wordplay.
'the writer' becomes 'iam' (I am not sure about this - if you are sure you should believe this answer much more).
'is taken aback' says the letters should be written in reverse.
'about' is an insertion indicator.
'periodically' means one should take alternating letters (letters must be selected 'every so often').
The alternate letters of 'harsh' are 'as'.
'iam' backwards is 'mai'.
'mai' placed around 'as' is 'MASAI'.
Can you help me to learn more?
(Other definitions for masai that I've seen before include "Africans" , "Pastoral people of East Africa - as I am (anag)" , "East African pastoralist" , "East African people" , "Member of an African pastoral people" .)