Fit to host just half of brunch — it's short (6)
I believe the answer is:
abrupt
'short' is the definition.
(abrupt can mean short or terse)
'fit to host just half of brunch' is the wordplay.
'fit' becomes 'apt' (apt means appropriate or fitting).
'to host' means one lot of letters goes inside another (inserted letters are hosted or welcomed).
'just half of' means to take half the letters.
'brunch' with half the letters taken is 'bru'.
'apt' placed around 'bru' is 'ABRUPT'.
'it's' acts as a link.
(Other definitions for abrupt that I've seen before include "Curt and short" , "Short in manner" , "Curt, sharp" , "Sudden, brusque" , "Unexpected -- precipitous" .)