Stuff happens in the middle after batting similarly in the morning (4)
I believe the answer is:
tamp
'stuff' is the definition.
(thesaurus)
'happens in the middle after batting similarly in the morning' is the wordplay.
'in the middle' says to take the centre.
'after' says to put letters next to each other.
'batting similarly' becomes 't' (I am not sure about this - if you are sure you should believe this answer much more).
'in the morning' becomes 'am' (AM on a clock).
The central letter of 'happens' is 'p'.
't'+'am'='tam'
'p' put after 'tam' is 'TAMP'.
(Other definitions for tamp that I've seen before include "press down firmly" , "Press, pack (down)" , "Pack or ram down tightly" , "Pack down eg tobacco in a pipe" , "Pat firmly (down)" .)