Harvestman regarding rotten pear (6)
I believe the answer is:
reaper
'harvestman' is the definition.
(I've seen this in another clue)
'regarding rotten pear' is the wordplay.
'regarding' becomes 're' ('re' means regarding or about).
'rotten' indicates an anagram.
'pear' is an anagram of 'aper'.
're'+'aper'='REAPER'
(Other definitions for reaper that I've seen before include "Death is described as a grim one" , "that you don't want to meet if it's grim" , "being grim when you're late" , "Death is known as a grim one" , "Farm machinery" .)