Humorous type's official warning? (7)
I believe the answer is:
caution
I believe this clue is a double definition.
'humorous type's' is the first definition.
(caution can mean a funny person)
'official warning?' is the second definition.
(eg on a sign)
(Other definitions for caution that I've seen before include "Circumspection" , "Admonish - warning" , "Warning - prudence" , "Caveat, prudence" , "Prudent wariness" .)