26 French spears dealt with intruder (10)
I believe the answer is:
trespasser
'intruder' is the definition.
('trespasser' can be a synonym of 'intruder')
'26 french spears dealt' is the wordplay.
'r6 french' becomes 'tres' (I can't justify this - if you can you should believe this answer much more).
'dealt' indicates an anagram.
'spears' with letters rearranged gives 'passer'.
'tres'+'passer'='TRESPASSER'
'with' is the link.
Can you help me to learn more?
(Other definitions for trespasser that I've seen before include "One entering land without permission" , "Illegal enterer of land" , "one of a number praying for forgiveness?" , "One unlawfully entering another's land" , "Uninvited visitor" .)