Act after article causes trouble (3)
I believe the answer is:
ado
'trouble' is the definition.
(both can mean bother or commotion)
'act after article' is the wordplay.
'act' becomes 'do' (to do is to act or execute a task).
'after' says to put letters next to each other.
'article' becomes 'a' (English indefinite article).
'do' put after 'a' is 'ADO'.
'causes' acts as a link.
(Other definitions for ado that I've seen before include "Shakespeare: 'Much ... About Nothing'(3) ()" , "stir" , "Fuss, difficulty" , "Flurry" , "Pother" .)