Rummage (5)
I believe the answer is:
delve
'rummage' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for delve that I've seen before include "Make painstaking enquiries (into something)" , "probe deeply" , "Intensively research (into something)" , "Dig - rummage" , "Look closely (into)" .)