Deliberately lose toss (5)
I believe the answer is:
throw
I believe this is a double definition.
'deliberately lose' is the first definition.
(I've seen this before)
'toss' is the second definition.
(thesaurus)
(Other definitions for throw that I've seen before include "Light cloth cover for furniture" , "Toss" , "Make a pot" , "Hurl; perplex" , "return from the boundary, perhaps" .)