Knocks the past, somehow (4)
I believe the answer is:
taps
'knocks' is the definition.
('tap' can be a synonym of 'knock')
'past somehow' is the wordplay.
'somehow' indicates an anagram.
'past' anagrammed gives 'TAPS'.
'the' is the link.
(Other definitions for taps that I've seen before include "Bugs (wire)" , "Thread cutters' strikes" , "Strikes lightly; eavesdropping devices" , "Bugs; valves" , "Military bugle call at dusk" .)