Meaningful study in a mess with voiding of contract, unfortunately (9)
I believe the answer is:
semantics
'meaningful study' is the definition.
(the academic study of meaning)
'in a mess with voiding of contract unfortunately' is the wordplay.
'with' says to put letters next to each other.
'voiding of' means to remove the middle letters.
'unfortunately' indicates an anagram (a bad or unfortunate spelling).
'contract' with its middle taken out is 'ct'.
'in'+'a'+'mess'+'ct'='inamessct'
'inamessct' with letters rearranged gives 'SEMANTICS'.
(Other definitions for semantics that I've seen before include "The meaning attached to words" , "Branch of linguistics concerned with meanings" , "Branch of linguistics to do with meaning" , "Main sects (anag.)" , "The significance of a text" .)