Etna erupted: large town shows resolve (8)
I believe the answer is:
tenacity
'resolve' is the definition.
(resolve can mean tenacity or determination)
'etna erupted large town' is the wordplay.
'erupted' indicates anagramming the letters (I've seen 'erupting' mean this).
'large town' becomes 'city' (I've seen this before).
'etna' is an anagram of 'tena'.
'tena'+'city'='TENACITY'
'shows' is the link.
(Other definitions for tenacity that I've seen before include "Stubbornness, determination" , "Perseverance in chosen course" , "Ability to stick firmly to task or position" , "Staying power" , "Persistent determination, doggedness" .)