Accompanying sketch is abstract (8)
I believe the answer is:
withdraw
'is abstract' is the definition.
(thesaurus)
'accompanying sketch' is the wordplay.
'accompanying' becomes 'with' (I've seen this before).
'sketch' becomes 'draw' (I've seen this in other clues).
'with'+'draw'='WITHDRAW'
(Other definitions for withdraw that I've seen before include "Pull back or move away" , "Recant" , "Remove, take away" , "Take money out of a bank account" , "Drop out" .)