Protesting vehemently, Pam ruins rambles (2,2,4)
I believe the answer is:
up in arms
'protesting vehemently' is the definition.
(up in arms means protesting)
'pam ruins rambles' is the wordplay.
'rambles' indicates an anagram.
'pam'+'ruins'='pamruins'
'pamruins' is an anagram of 'UP IN ARMS'.
(Other definitions for up in arms that I've seen before include "Outraged" , "Prepared to protest strongly" , "Openly protesting" , "Baby may be" , "Protesting strongly" .)