Judge nude emperor's "clothes" (4)
I believe the answer is:
deem
'judge' is the definition.
(I've seen this before)
'nude emperor's clothes' is the wordplay.
'clothes' indicates the answer is hidden within the clue (the letters clothe the hidden word).
'DEEM' is hidden in the letters of 'nude emperors'.
(Other definitions for deem that I've seen before include "Regard in a specific way" , "Card-table felt" , "Judge, think, consider" , "Judge in redeeming" , "Believe" .)