Predatory insect (6)
'predatory insect' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for mantis that I've seen before include "Predatory insect" , "Actually it preys rather than prays" , "Insect often seen in praying posture" , "It appears to be praying but is more likely preying" , "Large insect (sometimes praying?)" .)
'predatory insect' is the definition.
(dragonflies are predatory)
This is all the clue.
(Other definitions for dragonfly that I've seen before include "creature!" , "Large hovering insect" , "Large winged insect" , "Insect with two pairs of transparent wings" , "it wings along" .)