Official pitch inexperienced reporter typed up about waste (10)
I believe the answer is:
bureaucrat
'official' is the definition.
(a bureaucrat is a government official)
'pitch inexperienced reporter typed up about waste' is the wordplay.
'pitch' becomes 'tar' (synonyms).
'inexperienced reporter' becomes 'cub' (I've seen this in another clue).
'typed up' is a reversal indicator (in a down clue, letters go up).
'about' indicates putting letters inside.
'waste' becomes 'urea' (compound in urine).
'tar'+'cub'='tarcub'
'tarcub' back-to-front is 'bucrat'.
'bucrat' enclosing 'urea' is 'BUREAUCRAT'.
(Other definitions for bureaucrat that I've seen before include "Government official" , "Administrator" , "Mandarin" .)