Development of monster covered by heartless journalists (8)
I believe the answer is:
progress
'development' is the definition.
(progress is a kind of development)
'monster covered by heartless journalists' is the wordplay.
'monster' becomes 'ogre' ('ogre' can be a synonym of 'monster'**).
'covered by' indicates putting letters inside.
'heartless' means to remove the middle letters.
'journalists' becomes 'press' (I've seen this before).
'press' with its middle removed is 'prss'.
'ogre' placed inside 'prss' is 'PROGRESS'.
'of' is the link.
(Other definitions for progress that I've seen before include "Advance - promotion" , "Forward movement towards a destination or goal" , "Go on - journey" , "Get on with" , "Course" .)