Break in regularly after pinching item of jewellery (8)
I believe the answer is:
infringe
'break' is the definition.
(infringing is a kind of breaking)
'in regularly after pinching item of jewellery' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'pinching' is an insertion indicator (taking inside).
'item of jewellery' becomes 'ring' (I've seen this in other clues).
The alternating letters of 'after' are 'fe'.
'fe' placed around 'ring' is 'fringe'.
'in'+'fringe'='INFRINGE'
(Other definitions for infringe that I've seen before include "Break (rule)" , "Contravene" , "Break (eg, a law)" , "Transgress" , "Break the rules" .)