Notice valet weeping (7)
I believe the answer is:
'weeping' is the definition.
'notice valet' is the wordplay.
'notice' becomes 'see' (notice can mean to spot or see).
'valet' becomes 'page' (I've seen this in another clue).
(Other definitions for seepage that I've seen before include "Slow flow of fluid" , "Ooze" , "Discharge" , "narrow escape?" , "Leaking liquid" .)