After rout, oddly joke about approach (3-2)
I believe the answer is:
run-up
'approach' is the definition.
(I know that run-up is a type of approach)
'after rout oddly joke about' is the wordplay.
'after' says to put letters next to each other.
'oddly' indicates alternate letters (letters in odd-numbered positions).
'joke' becomes 'pun' (pun is a type of joke).
'about' says the letters should be written in reverse.
The alternating letters of 'rout' are 'ru'.
'pun' reversed gives 'nup'.
'ru'+'nup' is 'RUN-UP'.
(Other definitions for run-up that I've seen before include "Bowler's approach?" , "Cricketing approach?" , "Preliminary period" , "Approach - preliminaries" .)