Stiffeners for bald-headed people (6)
I believe the answer is:
braces
'stiffeners' is the definition.
Although both the answer and definition are plural nouns, I don't understand how one could define the other.
'bald-headed people' is the wordplay.
'bald-headed' becomes 'br' (I can't explain this - if you can you should give a lot more credence to this answer).
'people' becomes 'aces' (ace is a kind of person).
'br'+'aces'='BRACES'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for braces that I've seen before include "Appliances to correct dental irregularities" , "Supports for teeth or trousers" , "Dental appliances and pairs" , "Supports for men's trousers" , "stays" .)