A mixed grill, hot, short of nothing, OK? (3,5)
I believe the answer is:
all right
'ok?' is the definition.
('all-right' can be a synonym of 'ok')
'a mixed grill hot short of nothing' is the wordplay.
'mixed' indicates an anagram.
'short of' is a deletion indicator.
'nothing' becomes 'o' (looks like zero - 0).
'hot' with 'o' taken out is 'ht'.
'grill' is an anagram of 'llrig'.
'a'+'llrig'+'ht'='ALL-RIGHT'
(Other definitions for all right that I've seen before include "What's clearly acceptable" , "Agreed" , "Very well, I agree" , "Very well, everything's ok" , "none left" .)