Aha! That poet Ford moved without delay (2,3,4,2,1,3)
I believe the answer is:
at the drop of a hat
'without delay' is the definition.
(I've seen this before)
'aha that poet ford moved' is the wordplay.
'moved' is an anagram indicator.
'aha'+'that'+'poet'+'ford'='ahathatpoetford'
'ahathatpoetford' is an anagram of 'AT THE DROP OF A HAT'.
(Other definitions for at the drop of a hat that I've seen before include "Derby's relegation signalled thus" , "Immediately" , "without good reason?" , "When a tile descends" , "suddenly?" .)