Jersey, perhaps, odd — it's worn by relative (8)
I believe the answer is:
ruminant
'jersey perhaps' is the definition.
(I know that Jersey is a type of milker)
'odd it's worn by relative' is the wordplay.
'odd' becomes 'rum' (rum can mean strange or dubious).
'worn by' means one lot of letters goes inside another (I've seen this in other clues).
'relative' becomes 'nan' (I have seen 'Elderly relative' mean 'nan' so perhaps 'relative' could also mean 'nan').
'it' going around 'nan' is 'inant'.
'rum'+'inant'='RUMINANT'
(Other definitions for ruminant that I've seen before include "Cud chewing mammal" , "Mammal that chews the cud" , "Goat, say" , "Cud-chewing animal" , "Eg, sheep, giraffe, cow" .)