Admission in court's beginning to crack criminal cases (6)
I believe the answer is:
access
'admission' is the definition.
(I've seen this before)
'court's beginning to crack criminal cases' is the wordplay.
'beginning to' indicates taking the first letters.
'crack' is an insertion indicator (inserted letters go into a gap or crack).
'criminal' indicates an anagram.
The first letter of 'courts' is 'c'.
'cases' with letters rearranged gives 'acess'.
'c' placed inside 'acess' is 'ACCESS'.
'in' acts as a link.
(Other definitions for access that I've seen before include "Right or means of admittance" , "Admission" , "Means of entry, passage" , "fit" , "Doorway" .)