The last one was more friendly with (6)
I believe the answer is:
closer
'more friendly with' is the definition.
I can't judge whether this definition defines the answer.
'the last one' is the wordplay.
'the last' becomes 'close' (synonyms).
'one' becomes 'r' (I can't justify this - if you can you should believe this answer much more).
'close'+'r'='CLOSER'
'was' acts as a link.
Can you help me to learn more?
(Other definitions for closer that I've seen before include "Stuffier" , "not so remote" , "Nearer as to time or event" , "One who is skilled at bringing a business transaction to a satisfactory conclusion" , "one concludes" .)