Silver's underwear? (4,5)
I believe the answer is:
'silver's underwear?' is the definition.
'long johns' can be an answer for 'underwear?' (I've seen this before). I'm not sure about the 'silver's' bit.
'silver's underwear?' is the wordplay.
'silver' becomes 'long john' (I've seen this in another clue).
'underwear?' becomes 's' (I am not sure about this - if you are sure you should believe this answer much more).
Can you help me to learn more?
(Other definitions for long johns that I've seen before include "Old habits" , "warm clothing" , "Some underclothing" , "Warm underwear" , "Thermal underpants" .)