Fishy sarnie appeared (6)
I believe the answer is:
arisen
'appeared' is the definition.
(arise can mean to appear or crop up)
'fishy sarnie' is the wordplay.
'fishy' is an anagram indicator.
'sarnie' with letters rearranged gives 'ARISEN'.
(Other definitions for arisen that I've seen before include "Sprung up" , "(Has) come into view; (has) originated (from)" , "Gone up" , "Come to light" , "(Has) cropped up" .)