Old boys, tardy entering monastery dwellers not under orders (7)
I believe the answer is:
oblates
'monastery dwellers not under orders' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'old boys tardy entering' is the wordplay.
'old boys' becomes 'OBs' (OB is short for old boy).
'tardy' becomes 'late' (synonyms).
'entering' is an insertion indicator.
'obs' enclosing 'late' is 'OBLATES'.
Can you help me to learn more?
(Another definition for oblates that I've seen is " Religious types".)