Governor means to host convention (4)
I believe the answer is:
norm
'convention' is the definition.
(I've seen this in another clue)
'governor means to host' is the wordplay.
'to host' indicates a hidden word (I've seen 'hosts' mean this).
'NORM' is hidden in the letters of 'governor means'.
(Other definitions for norm that I've seen before include "Typical, usual" , "Bacterium, virus, etc" , "What is conventional, regular" , "Yardstick" , "Average result" .)