Vegetable that's all right in acre hit disastrously (9)
I believe the answer is:
artichoke
'vegetable' is the definition.
(artichoke is a kind of vegetable)
'all right in acre hit disastrously' is the wordplay.
'all right' becomes 'ok' ('ok' can be a synonym of 'all right').
'in' means one lot of letters goes inside another.
'disastrously' indicates anagramming the letters (I've seen this in other clues).
'acre'+'hit'='acrehit'
'acrehit' is an anagram of 'artiche'.
'ok' put into 'artiche' is 'ARTICHOKE'.
'that's' acts as a link.
(Other definitions for artichoke that I've seen before include "Globe, perhaps" , "Plant with large edible flower-head" , "Edible thistle-like bud" , "something often associated with Jerusalem" , "See 26" .)