Opposite of subtract (3)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
add
'opposite of subtract' is the definition.
('add' is the opposite to 'subtract')
This is all the clue.
(Other definitions for add that I've seen before include "Also" , "Tot; append" , "do some mathematics" , "Put together (numbers)" , "Count up" .)