Weapon used by gunners at a landing place (6)
I believe the answer is:
rapier
'weapon' is the definition.
(rapier is a kind of weapon)
'gunners at a landing place' is the wordplay.
'gunners' becomes 'RA' (Royal Artillery).
'at' is a charade indicator (letters next to each other).
'a landing place' becomes 'pier' (pier is a kind of landing place).
'ra'+'pier'='RAPIER'
'used by' is the link.
(Other definitions for rapier that I've seen before include "Straight sword with narrow blade" , "Straight narrow sword with two edges" , "Light sword" , "A small spring flower" , "Narrow sword with two-edged blade" .)