Tom possibly injured Paul with tip of this weapon (8)
I believe the answer is:
catapult
'weapon' is the definition.
(I've seen this before)
'tom possibly injured paul with tip of this' is the wordplay.
'tom possibly' becomes 'cat' (a tom is a male cat).
'injured' indicates an anagram.
'with' is a charade indicator (letters next to each other).
'tip of' suggests taking the first letters.
The first letter of 'this' is 't'.
'paul' with letters rearranged gives 'apul'.
'cat'+'apul'+'t'='CATAPULT'
(Other definitions for catapult that I've seen before include "Stone-throwing device" , "Slingshot" , "fling" , "Hurl forcibly as from sling" , "Weapon projecting stones" .)