50 per cent off? I’ll take that! (3,4)
I believe the answer is:
not half
'i'll take that' is the definition.
(both can be used to express agreement or approval)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for not half that I've seen before include "a less than fair split?" , "Rather! - less than 50%?" , "Very much, exceedingly" , "I couldn't agree more!" , "I agree 100%" .)