Thin point on weapon (6)
I believe the answer is:
narrow
'thin' is the definition.
('narrow' can be similar in meaning to 'thin')
'point on weapon' is the wordplay.
'point' becomes 'n' (N is an example).
'on' is a charade indicator (letters next to each other).
'weapon' becomes 'arrow' (arrow is a kind of weapon**).
'n'+'arrow'='NARROW'
(Other definitions for narrow that I've seen before include "Of limited width" , "Small in breadth" , "Having little breadth" , "Thin; taper" , "Strait or confined" .)