Tendency of old penny to chink (5)
I believe the answer is:
drift
'tendency' is the definition.
(I know that drift is a type of tendency)
'old penny to chink' is the wordplay.
'old penny' becomes 'd' (abbreviation for the pre-decimal penny).
'to chink' becomes 'rift' (I've seen this in another clue).
'd'+'rift'='DRIFT'
'of' is the link.
(Other definitions for drift that I've seen before include "aimless" , "Float along; heap of snow" , "Be powerless to control movement" , "state of indecision" , "See 8" .)