Short and sweet, not worth changing, so approved (8)
I believe the answer is:
assented
'approved' is the definition.
(to assent is to agree to something)
'short and sweet not worth changing' is the wordplay.
'not' is a deletion indicator.
'changing' indicates anagramming the letters.
'short'+'and'+'sweet'='shortandsweet'
'shortandsweet' with 'worth' removed is 'sandseet'.
'sandseet' is an anagram of 'ASSENTED'.
'so' acts as a link.
(Other definitions for assented that I've seen before include "Agreed to do something" , "Acquiesced" , "Consented" , "Given agreement" , "Acceded." .)