Sign language I read up about inspiring, originally (7)
I believe the answer is:
initial
'sign' is the definition.
(initial can mean to sign with an initial)
'language i read up about inspiring originally' is the wordplay.
'language' becomes 'latin' (Latin is an example).
'read up' says the letters should be written backwards (I've seen 'reading up' mean this (in a down clue, letters go up)).
'about' is an insertion indicator.
'originally' indicates taking the first letters.
The first letter of 'inspiring' is 'i'.
'latin'+'i'='latini'
'latini' written backwards gives 'inital'.
'inital' going around 'i' is 'INITIAL'.
(Other definitions for initial that I've seen before include "Sign" , "Relating to the beginning" , "Occurring at the start" , "First home, corgi, ultimately, wagging tail" , "Introductory" .)