Peephole for viewer to lease (6)
I believe the answer is:
eyelet
'peephole' is the definition.
(I've seen this in another clue)
'viewer to lease' is the wordplay.
'viewer' becomes 'eye' (organ which sees or views).
'to lease' becomes 'let' ('let' can be a synonym of 'lease').
'eye'+'let'='EYELET'
'for' is the link.
(Other definitions for eyelet that I've seen before include "Small hole through which a cord is passed" , "Small opening in shoe for lace" , "hole in shoe leather?" , "Small hole in needle for thread" , "Means of securing" .)