Slip through the cracks (4)
I believe the answer is:
seep
'slip through the cracks' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for seep that I've seen before include "Flow or leak slowly" , "Leak slowly, ooze" , "Leak gradually" , "Leak through an opening" , "dribble away" .)