Hole at the front (6)
I believe the answer is:
trench
This clue is a double definition.
'hole' is the first definition.
(thesaurus)
'at the front' is the second definition.
(I've seen this before)
(Other definitions for trench that I've seen before include "deep channel" , "Ditch dug as fortification" , "A military ditch for soldiers" , "depression" , "at the front" .)