Rod wearing a little old coat (6)
I believe the answer is:
tabard
'old coat' is the definition.
'rod wearing a little' is the wordplay.
'rod' becomes 'bar' (I've seen this before).
'wearing' means one lot of letters goes inside another.
'a little' becomes 'tad' (I've seen this before).
'bar' going inside 'tad' is 'TABARD'.
(Other definitions for tabard that I've seen before include "Jerkin; heraldic coat" , "Short sleeveless tunic" , "Sleeveless jerkin" , "Gilet" , "Short tunic, open at the sides" .)