Copy operatic heroine (contralto) (5)
I believe the answer is:
mimic
'copy' is the definition.
(mimicking is a kind of copying)
'operatic heroine contralto' is the wordplay.
'operatic heroine' becomes 'mimi'.
'contralto' becomes 'c' (musical abbreviation).
'mimi'+'c'='MIMIC'
(Other definitions for mimic that I've seen before include "Imitate satirically" , "Person imitating another" , "Imitate for humorous reasons" , "Imitate in order to ridicule" , "Take (someone) off" .)