Lie in wait with regular ammo in front of shrub (6)
I believe the answer is:
ambush
'lie in wait' is the definition.
(I've seen this before)
'regular ammo in front of shrub' is the wordplay.
'regular' means one should take alternating letters.
'in front of' is a charade indicator (letters next to each other).
'shrub' becomes 'bush' (synonyms).
The alternating letters of 'ammo' are 'am'.
'am'+'bush'='AMBUSH'
'with' is the link.
(Other definitions for ambush that I've seen before include "(Where enemies) lie in wait" , "raid" , "Scene of lying in wait" , "Surprise attack" , "Attack from concealed position" .)