Trips over foot barriers, spilling whiskey (5)
I believe the answer is:
falls
'trips over' is the definition.
(to trip over is to fall)
'foot barriers spilling whiskey' is the wordplay.
'foot' becomes 'f' (abbreviation).
'barriers' becomes 'walls'.
'spilling' is a deletion indicator (deleted letters spill out).
'whiskey' becomes 'W' (alpha bravo charlie delta ...).
'walls' with 'w' removed is 'alls'.
'f'+'alls'='FALLS'
(Other definitions for falls that I've seen before include "Cascade" , "suffers defeat" , "Plummets" , "Forces" , "Goes down" .)