Pair with one friend's ape (7)
I believe the answer is:
primate
'ape' is the definition.
(thesaurus)
'pair with one friend's' is the wordplay.
'pair' becomes 'pr' (abbreviation).
'with' says to put letters next to each other.
'one' becomes 'i' (Roman numeral).
'friend' becomes 'mate' (mate is a kind of friend).
'pr'+'i'+'mate'='PRIMATE'
(Other definitions for primate that I've seen before include "Mammal such as human" , "Man in the mitre" , "Bishop; large mammal" , "Highest-ranking bishop" , "Archbishop of York, for example" .)