Stupid to be so worried about you crossing the Channel (6)
I believe the answer is:
obtuse
'stupid' is the definition.
(similar in meaning)
'be so worried about you crossing the channel' is the wordplay.
'worried' indicates an anagram (worry can mean to interfere with or disturb).
'about' means one lot of letters goes inside another.
'you' becomes 'u' (commonly used in online communication).
'crossing' means one lot of letters goes inside another (to cross can mean to go over or around).
'the channel' becomes 't' (I am not sure about this - if you are sure you should believe this answer much more).
'be'+'so'='beso'
'beso' anagrammed gives 'obse'.
'obse' going around 'u' is 'obuse'.
'obuse' enclosing 't' is 'OBTUSE'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for obtuse that I've seen before include "Angle greater than 90 degrees" , "Annoyingly slow to understand" , "Blunt, not sharp or pointed" , "Blunt, not sensitive" , "Orchestra; stripe" .)