Overheard, entirely, commands in Sacrament of Ordination (4,6)
I believe the answer is:
holy orders
'sacrament of ordination' is the definition.
'holy orders' can be an answer for 'ordination' (thesaurus). I'm unsure of the 'sacrament of' bit.
'overheard entirely commands' is the wordplay.
'overheard' indicates a 'sounds like' (homophone) clue.
'entirely' becomes 'wholly' (I've seen this before).
'commands' becomes 'orders' (order is a kind of command).
'wholly' is a homophone of 'holy'.
'holy'+'orders'='HOLY ORDERS'
'in' is the link.
Can you help me to learn more?
(Other definitions for holy orders that I've seen before include "papal bulls" , "Novices may take these" , "that minister takes" .)