What's sought by government dissembler turning up? (5)
I believe the answer is:
Here is my best explanation:
'what's sought' is the definition.
(in a phrase like 'the holy grail of science')
'government dissembler turning up?' is the subsidiary indication.
'government' becomes 'g'.
'dissembler' becomes 'liar' (I've seen this before).
'turning up?' says the letters should be written in reverse.
'liar' in reverse letter order is 'rail'.
'by' is the link.
(Other definitions for grail that I've seen before include "what some look for", "Fabled holy vessel", "Cup", "The holy chalice used by Christ at the Last Supper", "Holy vessel used at the Last Supper", "Object of knightly quest", "Cherished goal", "Holy object of quest", "The Holy ..., the legendary chalice used at the Last Supper" and "Famous chalice".)