Barbie's partner wears fashionable second layers (8)
I believe the answer is:
chickens
'layers' is the definition.
The definition and answer can be both animals as well as being plural nouns.
Maybe you can see an association between them that I don't see?
'barbie's partner wears fashionable second' is the wordplay.
'barbie's partner' becomes 'ken' (I can't explain this - if you can you should give a lot more credence to this answer).
'wears' means one lot of letters goes inside another.
'fashionable' becomes 'chic' (I've seen this before).
'second' becomes 's' (common abbreviation).
'chic'+'s'='chics'
'ken' going inside 'chics' is 'CHICKENS'.
Can you help me to learn more?
(Other definitions for chickens that I've seen before include "farmyard animals?" , "Scaredy cats" , "Yellow" , "Young fowl" , "Hens" .)