This we can say about your underwear? (1-6)
I believe the answer is:
y-fronts
'underwear?' is the definition.
(type of underwear)
'this we can say about your' is the wordplay.
I cannot quite see how this works, but
'about' could be 'on' (as in a book 'on' a certain topic) and 'on' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for y-fronts that I've seen before include "Pants for men" , "Type of underpants" , "Item of male underwear" , "Item of male clothing" , "Men's pants" .)