I mention Dicky instantly (2,2,4)
I believe the answer is:
in no time
'instantly' is the definition.
(thesaurus)
'i mention dicky' is the wordplay.
'dicky' indicates an anagram (dicky can mean ill or non-functioning).
'mention' is an anagram of 'nnotime'.
'i'+'nnotime'='IN NO TIME'
(Other definitions for in no time that I've seen before include "Very rapidly, hardly measurable" , "Very rapidly - but sounds impossible?" , "Without delay, too quick to measure" , "Swiftly" , "Immediately" .)