Sinead sorted out grasping Tory very quickly (2,1,6)

'very quickly' is the definition.
(I've seen this in another clue)

'sinead sorted out grasping tory' is the wordplay.
'sorted out' is an anagram indicator.
'grasping' is an insertion indicator (inserted letters are held or grasped).
'tory' becomes 'con' (abbreviation for conservative).
'sinead' anagrammed gives 'inased'.
'inased' placed around 'con' is 'IN A SECOND'.