For pests, a rising star! (4)
I believe the answer is:
rats
'for pests' is the definition.
The answer and definition can be both people as well as being plural nouns.
Perhaps you can see an association between them that I can't see?
'a rising star' is the wordplay.
'a rising' says the letters should be written backwards (letters written upwards in a down clue).
'star' back-to-front is 'RATS'.
Can you help me to learn more?
(Other definitions for rats that I've seen before include "Oh no" , "were piped away" , "Hamelin's pests" , "First word of 'The 21 19'" , "Blast" .)