Extent of suspicion about Democrat (7)
I believe the answer is:
breadth
'extent' is the definition.
(thesaurus)
'suspicion about democrat' is the wordplay.
'suspicion' becomes 'breath' (I've seen this in other clues).
'about' means one lot of letters goes inside another.
'democrat' becomes 'd'.
'breath' enclosing 'd' is 'BREADTH'.
'of' acts as a link.
(Other definitions for breadth that I've seen before include "Liberality" , "Wide range" , "Lateral extent" , "generosity of mind" , "Extent from side to side" .)