Sentence:  "Insane Roman! (4)" ... Look in "-sane Roman" and you'll uncover NERO, the "insane Roman". Dovetailing the signpost &mdash; "in" &mdash; with the hidden <WSD>fodder</WSD> &mdash; "sane Roman" &mdash; is inspired, an embedded style of signposting. 
Meaning of the word marked with <WSD> tags:  The text to be operated on (anagrammed, etc.) within a clue.