Hackneyed phrase (6)
I believe the answer is:
cliche
'hackneyed phrase' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for cliche that I've seen before include "Saying made tedious through over-use" , "Stereotyped expression" , "Commonplace remark, banality" , "Hackneyed idea, plot etc" , "Saying repeated too often" .)