Row and draw revolver at the front (4)
I believe the answer is:
tier
'row' is the definition.
(a tier is a row of things)
'draw revolver at the front' is the wordplay.
'draw' becomes 'tie' (synonyms).
'at the front' suggests taking the first letters.
The first letter of 'revolver' is 'r'.
'tie'+'r'='TIER'
'and' acts as a link.
(Other definitions for tier that I've seen before include "One who secures" , "Rank, level" , "'Level, grade (4)'" , "Row, layer" , "Level within hierarchy" .)