Discern advertisement (6)
I believe the answer is:
notice
I believe this is a double definition.
'discern' is the first definition.
(thesaurus)
'advertisement' is the second definition.
(I've seen this before)
(Other definitions for notice that I've seen before include "'Observe, discern (6)'" , "Warning - observe - review" , "Advance warning of job resignation" , "Advance indication of intention to resign" , "Remark upon; small advertisement" .)