Democrat at fault reveals tendency (5)
I believe the answer is:
drift
'tendency' is the definition.
(I know that drift is a type of tendency)
'democrat at fault' is the wordplay.
'democrat' becomes 'd'.
'at' means one lot of letters go next to another.
'fault' becomes 'rift' (as in a fault line).
'd'+'rift'='DRIFT'
'reveals' acts as a link.
(Other definitions for drift that I've seen before include "non-standard deviation?" , "state of indecision" , "Gist - snow" , "Meander aimlessly" , "Move casually or aimlessly" .)