City children (not just one of them) outside old university (5)
I believe the answer is:
rouen
'city' is the definition.
(Rouen is a French city)
'them outside old university' is the wordplay.
'them' becomes 'ren' (I can't justify this - if you can you should give a lot more credence to this answer).
'outside' indicates putting letters inside.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'university' becomes 'u' (abbreviation for university).
'o'+'u'='ou'
'ren' going around 'ou' is 'ROUEN'.
'children not just one of' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for rouen that I've seen before include "City in northern France" , "French community" , "Port on river Seine" , "French city where Joan of Arc was burned" , "French cathedral city" .)