This minute chicken's split at the back? (2,3,4)
I believe the answer is:
on the nail
'this minute' is the definition.
(on the nail means immediately)
'chicken's split at the back?' is the wordplay.
'chicken' becomes 'hen' (hen is a kind of chicken).
'split' indicates putting letters inside (some letters split a word into two).
'at' becomes 'on' (location).
'the back?' becomes 'tail' (tail is a kind of back).
'on'+'tail'='ontail'
'hen' put within 'ontail' is 'ON THE NAIL'.
(Other definitions for on the nail that I've seen before include "Where varnish is put" , "Exact" , "without delay" , "Where a coat may be hung" , "Exactly" .)