Rampant male featured in piece I'd prepared (8)
I believe the answer is:
epidemic
'rampant' is the definition.
(thesaurus)
'male featured in piece i'd prepared' is the wordplay.
'male' becomes 'm' (common abbreviation).
'featured in' is an insertion indicator.
'prepared' is an anagram indicator.
'piece'+'id'='pieceid'
'pieceid' with letters rearranged gives 'epideic'.
'm' placed within 'epideic' is 'EPIDEMIC'.
(Other definitions for epidemic that I've seen before include "Disease affecting many in a population at the same time" , "spreading disease" , "Prevalent disease" , "Prevailing" , "Outbreak of disease which spreads rapidly" .)