Father and I with close acquaintance (6)
I believe the answer is:
friend
'acquaintance' is the definition.
(I know that acquaintance can be written as friend)
'father and i with close' is the wordplay.
'father' becomes 'fr' (abbreviation as in a priest's title).
'and' says to put letters next to each other.
'with' says to put letters next to each other.
'close' becomes 'end' (close can mean to end or finish).
'fr'+'i'+'end'='FRIEND'
(Other definitions for friend that I've seen before include "Close associate" , "Pal, mate" , "Comrade for finder" , "Associate, supporter" , "China" .)