Odd parts of champ’s headgear (3)
I believe the answer is:
cap
'headgear' is the definition.
(I know that cap is a type of headgear)
'odd parts of champ's' is the wordplay.
'odd parts of' indicates alternate letters.
The alternate letters of 'champs' are 'CAP'.
(Other definitions for cap that I've seen before include "Dental work" , "Covering for head or bottle" , "Soft headgear" , "Peaked hat" , "Stopper" .)