Sitcom in which mad criminal seizes country (7)
I believe the answer is:
miranda
'sitcom' is the definition.
(I know that Miranda is a sitcom)
'mad criminal seizes country' is the wordplay.
'criminal' indicates an anagram.
'seizes' is an insertion indicator.
'country' becomes 'iran' (Iran is a country).
'mad' anagrammed gives 'mda'.
'mda' enclosing 'iran' is 'MIRANDA'.
'in which' is the link.
(Other definitions for miranda that I've seen before include "Prospero's daughter (Tempest)" , "girl" , "Heroine of The Tempest" , "Innocent heroine" , "Prospero's daughter (The?Tempest)" .)