Managed company with utter heartless resentment (7)
I believe the answer is:
rancour
'resentment' is the definition.
('rancour' can be a synonym of 'resentment')
'managed company with utter heartless' is the wordplay.
'managed' becomes 'ran' (I've seen this before**).
'company' becomes 'co' (abbreviation).
'with' means one lot of letters go next to another.
'heartless' suggests removing the centre.
'utter' with its centre removed is 'ur'.
'ran'+'co'+'ur'='RANCOUR'
(Other definitions for rancour that I've seen before include "Acrimony" , "Animosity" , "Deep-seated enmity" , "Malicious hostility" , "Malice" .)