Untouchable bag on front of desk (6)
I believe the answer is:
sacred
'untouchable' is the definition.
(I've seen this in another clue)
'bag on front of desk' is the wordplay.
'bag' becomes 'sac' (a small bag).
'on' becomes 're' ('on' can be mean 'with reference to').
'front of' indicates taking the first letters.
The first letter of 'desk' is 'd'.
'sac'+'re'+'d'='SACRED'
(Other definitions for sacred that I've seen before include "Sanctified" , "not to be interfered with?" , "Religious" , "Like gravestones maybe" , "Hallowed, consecrated" .)