Really digging (4)
I believe the answer is:
into
'really digging' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for into that I've seen before include "Taking an active and lively interest (in something)" , "ignition regularly missing" , "Keen on, colloquially" , "Enthusiastic about" , "To a position inside" .)