Work briefly on examination of part of the head (8)
I believe the answer is:
temporal
'of part of the head' is the definition.
(temporal can mean relating to the temples)
'work briefly on examination' is the wordplay.
'work briefly' becomes 'temp' (temp can mean to work somewhere temporarily).
'on' is a charade indicator (letters next to each other).
'examination' becomes 'oral' (oral is a kind of examination).
'temp'+'oral'='TEMPORAL'
(Other definitions for temporal that I've seen before include "Relating to time" , "Nothing spiritual" , "Passing" , "Not eternal" , "Of wordly affairs, not spiritual" .)