Send up topless overall (4)
I believe the answer is:
mock
'send up' is the definition.
(thesaurus)
'topless overall' is the wordplay.
'topless' means to remove the first letter.
'overall' becomes 'smock'.
'smock' with its initial letter removed is 'MOCK'.
(Other definitions for mock that I've seen before include "Deride - false" , "Unreal; ridicule" , "Imitation; tease scornfully" , "Not real, ridicule" , "Tease - fake" .)