Provide for one’s children (5)
I believe the answer is:
issue
'children' is the definition.
(issue can mean someone's offspring)
'provide for one's' is the wordplay.
'provide' becomes 'sue' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'for' means one lot of letters go next to another (I've seen this in other clues).
'one's' becomes 'i's' (Roman numeral).
'sue' after 'is' is 'ISSUE'.
Can you help me to learn more?
(Other definitions for issue that I've seen before include "Topic; give out" , "Matter of contention" , "Offspring or edition" , "Sprogs" , "Children; topic for debate" .)