Almost engross friend and finish (10)
I believe the answer is:
consummate
'finish' is the definition.
(I know that consummate is a more specific form of the action accomplish)
'almost engross friend' is the wordplay.
'almost' means to remove the last letter (almost the whole word is kept).
'engross' becomes 'consume' (consuming is a kind of engrossing).
'friend' becomes 'mate' (mate is a kind of friend).
'consume' with its final letter taken off is 'consum'.
'consum'+'mate'='CONSUMMATE'
'and' is the link.
(Other definitions for consummate that I've seen before include "total" , "Showing great skill and flair" , "Supreme, perfect; make (a marriage) complete" .)