Affected by trichinosis - almost collapsing (10)
I believe the answer is:
histrionic
'affected' is the definition.
(thesaurus)
'trichinosis almost collapsing' is the wordplay.
'almost' means to remove the last letter (most of the word but not all of it).
'collapsing' is an anagram indicator.
'trichinosis' with its final letter taken off is 'trichinosi'.
'trichinosi' with letters rearranged gives 'HISTRIONIC'.
'by' is the link.
(Other definitions for histrionic that I've seen before include "Overly theatrical" , "Of acting; dramatic" , "Melodramatic" .)