General disorder? That's swell (7)
I believe the answer is:
enlarge
'swell' is the definition.
(swell can mean to get bigger)
'general disorder?' is the wordplay.
'disorder?' indicates an anagram (I've seen 'disorder' mean this (a disordered version of the letters)).
'general' with letters rearranged gives 'ENLARGE'.
'that's' is the link.
(Other definitions for enlarge that I've seen before include "Wax" , "Describe in more detail" , "Make greater" , "Gleaner (anag.)" , "Expand" .)