Take legal action following one's publication (5)
I believe the answer is:
issue
'publication' is the definition.
(issue is a kind of publication)
'take legal action following one's' is the wordplay.
'take legal action' becomes 'sue' (I've seen this before).
'following' says to put letters next to each other.
'one's' becomes 'is' (roman numeral).
'sue' after 'is' is 'ISSUE'.
(Other definitions for issue that I've seen before include "Important topic for offspring" , "Number (of periodical)" , "Important problem" , "Spring - children - publication" , "Offspring or edition" .)