Iron rod turned on a hat (6)
I believe the answer is:
fedora
'hat' is the definition.
(I know that fedora is a type of hat)
'iron rod turned on a' is the wordplay.
'iron' becomes 'Fe' (chemical symbol for iron).
'turned' says the letters should be written backwards.
'on' means one lot of letters go next to another (in a down clue, letters appear on others).
'rod' written backwards gives 'dor'.
'fe'+'dor'+'a'='FEDORA'
(Other definitions for fedora that I've seen before include "Felt hat dented sideways" , "Felt hat much loved by 1930s gangsters" , "Hat for RAF doe" , "Read of (anag) - brimmed felt hat" , "O, Fred, a hat becomes you" .)