Peruse some rare advertisements (4)
I believe the answer is:
read
'peruse' is the definition.
(I've seen this in another clue)
'some rare advertisements' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'READ' is hidden within 'rare advertisements'.
(Other definitions for read that I've seen before include "Speak" , "Con" , "Lecture" , "Check, emend (proof)" , "Looked at and understood" .)