Clue: Mythical sea monster, camouflaged — blooming thing! (6)
Answer: ORCHID
Explanation: Mythical sea monster, camouflaged — blooming thing! (6)
**ORC **("mythical sea creature") + **HID **("camouflaged") 
"Orc" as a mythical sea monster is a rare reference, with Orcs are more commonly associated with ogre-like creatures in the stories of Perrault and Tolkien.