Consumes a portion of steakhouse supper (4,2)
I believe the answer is:
uses up
'consumes' is the definition.
('use up' can be a synonym of 'consume')
'a portion of steakhouse supper' is the wordplay.
'a portion of' indicates the answer is hidden within the clue.
'USES UP' can be found hidden inside 'steakhouse supper'.
(Other definitions for uses up that I've seen before include "'Depletes (4,2)'" , "Consumes" , "drains" , "Exhausts" .)