Instruction: change it somehow (8)
I believe the answer is:
teaching
'instruction' is the definition.
('teaching' can be a synonym of 'instruction')
'change it somehow' is the wordplay.
'somehow' is an anagram indicator.
'change'+'it'='changeit'
'changeit' anagrammed gives 'TEACHING'.
(Other definitions for teaching that I've seen before include "Instructing" , "form of education" , "Imparting skills or knowledge" , "Training" , "exercise ..." .)