Intended heartlessly to follow United as a penance (9)
I believe the answer is:
atonement
'a penance' is the definition.
(thesaurus)
'intended heartlessly to follow united' is the wordplay.
'intended' becomes 'meant' (meaning is a kind of intending).
'heartlessly' suggests removing the centre.
'to follow' says to put letters next to each other.
'united' becomes 'atone' ('at one' can mean connected or united).
'meant' with its centre removed is 'ment'.
'ment' after 'atone' is 'ATONEMENT'.
'as' acts as a link.
(Other definitions for atonement that I've seen before include "Compensation for a wrong" , "needed to make amends" , "Expiation of sin, penance" , "Reparation (for a wrong)" , "reparations?" .)