Pass over some sign or expression (6)
I believe the answer is:
ignore
'pass over' is the definition.
(thesaurus)
'some sign or expression' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'IGNORE' is hidden in the letters of 'sign or expression'.
(Other definitions for ignore that I've seen before include "Refuse to notice or acknowledge" , "set aside" , "'Disregard, overlook (6)'" , "Deliberately overlook" , "Intentionally disregard" .)