Precursor to dismissal for offending party?
A cryptic piece.
A yellow card is a warning or precursor to a red card which leads to dismissal.
A party is a person in dispute with a referee or adjudicator

Boisterous rally cowed by warning note from official
Boisterous = anagram indicator 
rally cowed = anagram fodder 
by = necessary word
Warning note from official = Yellow Card

Weak programme of events? treat with caution! 
Additive or charade 
Weak = Yellow, programme of events = Card
Treat with caution = verbal form of yellow card