Mature insect, some claim - a good example (5)
I believe the answer is:
imago
'mature insect' is the definition.
(I've seen this in another clue)
'some claim a good example' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'IMAGO' is hidden in the letters of 'claim a good example'.
(Other definitions for imago that I've seen before include "idealised figure" , "picture of important person" , "Maybe comma" , "Final stage of insect development" , "Insect's adult stage" .)