Fish appearing odd in a dress (8)
I believe the answer is:
sardines
'fish' is the definition.
(I've seen this before)
'odd in a dress' is the wordplay.
'odd' indicates an anagram.
'in'+'a'+'dress'='inadress'
'inadress' anagrammed gives 'SARDINES'.
'appearing' is the link.
(Other definitions for sardines that I've seen before include "Young pilchards" , "Children's game - fish" , "Small fish, usually canned" , "Cumulative hiding game" , "Squash-together party game" .)