Unfortunately, son, I can't approve (8)
I believe the answer is:
sanction
'approve' is the definition.
(I know that sanction is a type of approve)
'unfortunately son i can't' is the wordplay.
'unfortunately' is an anagram indicator (a bad or unfortunate spelling).
'son'+'i'+'cant'='sonicant'
'sonicant' anagrammed gives 'SANCTION'.
(Other definitions for sanction that I've seen before include "Threatened penalty; official permission" , "Endorsement" , "OK" , "Authorisation" , "Official permission or authority" .)