Dad, accepting banter, ultimately becoming more distant (7)
I believe the answer is:
farther
'more distant' is the definition.
(more far away)
'dad accepting banter ultimately' is the wordplay.
'dad' becomes 'father' (I've seen this in another clue).
'accepting' means one lot of letters goes inside another (inserted letters are accepted).
'ultimately' suggests the final letters.
The last letter of 'banter' is 'r'.
'father' enclosing 'r' is 'FARTHER'.
'becoming' is the link.
(Other definitions for farther that I've seen before include "Beyond; her raft (anag)" , "Over a greater distance" , "longer" , "More distant" .)