Inspector could turn very sour (8)
I believe the answer is:
surveyor
'inspector' is the definition.
(I've seen this before)
'turn very sour' is the wordplay.
'turn' indicates an anagram.
'very'+'sour'='verysour'
'verysour' anagrammed gives 'SURVEYOR'.
'could' acts as a link.
(Other definitions for surveyor that I've seen before include "Person who examines the condition of land and buildings" , "Building inspector" , "Engineer who provides map-making data" , "Building examiner" , "Very sour kind of land inspector" .)