Subtract (6)
'subtract' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for take away that I've seen before include "Remove - portable meals" , "Minus" , "Subtract - fast food" , "Remove - portable food" .)
(Other definitions for minus that I've seen before include "(Of temperature) below zero" , "deficiency" , "Reduced by the subtraction of - thus?" , "Lacking; below zero" , "'Take away' sign" .)
(Other definitions for debit that I've seen before include "Payment made or owed" , "It's not to one's credit" , "Deduct from account" , "Accounting entry recording sums that are 5" , "Entry in account book of sum owed" .)
'subtract' is the definition.
(synonyms)
This is all the clue.
(Other definitions for deduct that I've seen before include "Remove" , "Knock off" , "Withhold" , "Subtract, take away" , "Make a subtraction" .)