Ruling out of overfishing could be smashing (9)
I believe the answer is:
shivering
'be smashing' is the definition.
Both the answer and definition are adjectives. Perhaps you can see a link between them that I can't see?
'ruling out of overfishing' is the wordplay.
I cannot quite see how this works, but
'ruling' could be 'in' (the ruling party is voted 'in') and 'in' is found within the answer.
This explanation may well be incorrect...
'could' is the link.
Can you help me to learn more?
(Other definitions for shivering that I've seen before include "trembling?" , "excited" , "Evidently cold" , "Shaking (with the cold)" .)