Input data:
abcdef_fhj_viji.dvc
Expected output:
fhj_viji.dvc
The part to be trimmed is not constant.
select substr('abcdef_fhj_viji.dvc',instr('abcdef_fhj_viji.dvc','_')+1) from dual
So, Its all depends on INSTR function, define from which position and which occurrence, you will get the index and pass that index to SUBSTR to get your string.
INSTR
SUBSTR