Addict wants cordial -- it's easy to understand (4-8)
I believe the answer is:
user-friendly
'easy to understand' is the definition.
(I've seen this before)
'addict wants cordial' is the subsidiary indication.
'addict' becomes 'user' (I've seen this before).
'wants' says to put letters next to each other.
'cordial' becomes 'friendly' ('friendly' can be similar in meaning to 'cordial'**).
'user'+'friendly'='userfriendly'
'it's' is the link.
(Other definitions for user-friendly that I've seen before include "Easy to operate" , "Easily picked up" , "Easy to understand or manipulate" .)