An overdue reform effort (9)
I believe the answer is:
endeavour
'effort' is the definition.
(I know that effort can be written as endeavour)
'an overdue reform' is the wordplay.
'reform' is an anagram indicator (letters in a new form).
'an'+'overdue'='anoverdue'
'anoverdue' anagrammed gives 'ENDEAVOUR'.
(Other definitions for endeavour that I've seen before include "Captain Cook's first ship - DCI Morse's first name" , "Cook's old vessel" , "famous ship" , "Determined effort" , "hard work" .)