Adult insect spotted a minute earlier (5)
I believe the answer is:
imago
'adult insect' is the definition.
(I've seen this in another clue)
'spotted a minute earlier' is the wordplay.
'spotted a minute' becomes 'im' (I can't justify this - if you can you should give a lot more credence to this answer).
'earlier' becomes 'ago' (I've seen this in another clue).
'im'+'ago'='IMAGO'
Can you help me to learn more?
(Other definitions for imago that I've seen before include "Mature insect stage" , "Winged insect -- amigo (anag)" , "Beetle, for example" , "picture of important person" , "Last stage of adult insect" .)