Convents' women in orders about northern lake (9)
I believe the answer is:
nunneries
'convents'' is the definition.
(nunnery is a kind of convent)
'women in orders about northern lake' is the wordplay.
'women in orders' becomes 'nuns' (I can't explain this - if you can you should give a lot more credence to this answer).
'about' indicates putting letters inside.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'lake' becomes 'erie' (Lake Erie is one of the Canadian/US 'Great Lakes').
'n'+'erie'='nerie'
'nuns' placed around 'nerie' is 'NUNNERIES'.
Can you help me to learn more?
(Another definition for nunneries that I've seen is " sisters here?".)