"Weapon" there is a wry smile about (7)
I believe the answer is:
missile
'weapon' is the definition.
(I know that missile is a type of weapon)
'is a wry smile about' is the wordplay.
'a wry' indicates an anagram (wry can mean twisted or distorted).
'about' means one lot of letters goes inside another.
'smile' anagrammed gives 'msile'.
'is' placed into 'msile' is 'MISSILE'.
'there' is the link.
I am not very happy about this link. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for missile that I've seen before include "Object forcibly propelled at a target" , "Weapon that is propelled" , "Military projectile" , "Weapon that's thrown or projected" , "One could get fired" .)