Double feature cheers (4-4)
I believe the answer is:
chin-chin
'cheers' is the definition.
(I've seen this before)
'double feature' is the wordplay.
'double' shows that letters should be duplicated.
'feature' becomes 'chin' (chin is a kind of feature).
'chin' doubled is 'CHIN-CHIN'.
(Other definitions for chin-chin that I've seen before include "Down the hatch!" , "Cheers, bottoms up" , "good health ..." .)