Detailed petition after test case (7)
I believe the answer is:
example
'case' is the definition.
(I know that case can be written as example)
'detailed petition after test' is the wordplay.
'detailed' means to remove the last letter (the word must be end-less or 'de-tailed').
'petition' becomes 'plea' (petition can mean to plea or beg).
'after' means one lot of letters go next to another.
'test' becomes 'exam' (synonyms).
'plea' with its final letter taken away is 'ple'.
'ple' after 'exam' is 'EXAMPLE'.
(Other definitions for example that I've seen before include "Case in point" , "not the actual version" , "Thing characteristic of its kind" , "Representative object" , "lesson" .)