Stalwart's whip broke the camel's back (4,5)
I believe the answer is:
last straw
'broke the camel's back' is the definition.
The answer and definition are not the same part of speech. However, I know that 'camel' relates to this answer.
'stalwart's whip' is the wordplay.
'whip' is an anagram indicator (I've seen 'whipped' mean this).
'stalwarts' anagrammed gives 'LAST STRAW'.
Can you help me to learn more?
(Other definitions for last straw that I've seen before include "drinker was lucky to get?" , "too much to bear?" , "Something that finally makes a situation intolerable" , "The final irritation that stretches your patience beyond the limit" , "camel's killer" .)