Outstanding insect abandons one girl and accepts another (7)
I believe the answer is:
classic
'outstanding' is the definition.
(thesaurus)
'insect abandons one girl and accepts another' is the wordplay.
I cannot quite understand how this works, but
'one' could be 'i' (roman numeral) and 'i' is present in the answer.
'girl' could be 'lass' (lass is a kind of girl) and 'lass' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for classic that I've seen before include "Work of enduring excellance" , "The Derby or The Oaks, for example" , "Model" , "Race, eg Derby" , "First-class" .)