Inspector, formerly a Bevin Boy? (8)
I believe the answer is:
Here is my best explanation:
'inspector' is the definition.
('examiner' can be a synonym of 'inspector')
'formerly a bevin boy?' is the subsidiary indication.
'formerly' becomes 'ex'.
'bevin boy?' becomes 'miner' (I've seen this before).
(Other definitions for examiner that I've seen before include "Tester of knowledge", "One looks for information", "Person testing", "Assessor", "judge", "Test setter", "One who tests, inspects or inquires into", "One administering test", "Academic tester" and "He gives you paper".)