Fancy pheromone contains secret message (6)
I believe the answer is:
cypher
'secret message' is the definition.
(message in code)
'fancy pheromone contains' is the wordplay.
'contains' indicates a hidden word.
'CYPHER' can be found hidden inside 'fancy pheromone'.
(Other definitions for cypher that I've seen before include "Code; unimportant person" , "Secret code (variant spelling)" , "Secret way of writing" .)