If you ruin a cigar with a tin opener, it's very sad (6)
I believe the answer is:
tragic
'very sad' is the definition.
(tragic can mean very sad or unfortunate)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for tragic that I've seen before include "heartbreaking" , "Awful" , "Terrible" , "Shocking" , "Intensely sad and distressing" .)