Lava turned up? Notices me after eruption (6,5)
I believe the answer is:
pumice stone
'lava' is the definition.
(I have seen 'Abrasive lava ' mean 'pumice stone' so perhaps 'lava' could also mean 'pumice stone')
'turned up? notices me after eruption' is the wordplay.
'turned' shows that the letters should be reversed in order.
'after eruption' indicates anagramming the letters (I've seen this in other clues).
'up' written backwards gives 'pu'.
'notices'+'me'='noticesme'
'noticesme' with letters rearranged gives 'micestone'.
'pu'+'micestone'='PUMICE-STONE'
(Other definitions for pumice stone that I've seen before include "Light volcanic rock" , "Lava used as abrasive" .)