When children are about the dog is tied up (7)
I believe the answer is:
secured
'when children' is the definition.
I can't tell whether this defines the answer.
'about the dog is tied up' is the wordplay.
'about' indicates putting letters inside.
'the dog' becomes 'cur' (both can mean a despicable person).
'is tied up' becomes 'seed' (I can't justify this - if you can you should give a lot more credence to this answer).
'cur' inserted into 'seed' is 'SECURED'.
'are' is the link.
Can you help me to learn more?
(Other definitions for secured that I've seen before include "Made safe or fastened safely" , "Seized" , "locked up" , "Gained" , "all tied up?" .)