Adult (5)
'adult' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for imago that I've seen before include "latest development in cricket?" , "butterfly, for example" , "Last state of insect life" , "Final stage of insect life" , "Mature insect stage" .)
'adult' is the definition.
(I know that adult can be written as grown-up)
This is the entire clue.
(Other definitions for grown-up that I've seen before include "Matured" , "Big" , "Fully developed person" , "Mature" , "Adult" .)