Disguise a tray carrying a singlet (8)
I believe the answer is:
travesty
'disguise' is the definition.
(thesaurus)
'a tray carrying a singlet' is the wordplay.
'carrying' indicates putting letters inside.
'a singlet' becomes 'vest' ('vest' can be a synonym of 'singlet').
'tray' going around 'vest' is 'TRAVESTY'.
(Other definitions for travesty that I've seen before include "Absurd misrepresentation" , "Total misrepresentation" , "Farcical imitation" , "Burlesque, parody" , "Charade" .)