Economist a forger, eating bananas up (4)
'economist' is the definition.
(I've seen this before)
'a forger eating bananas up' is the wordplay.
'forger' becomes 'smith' (I've seen this before).
'eating' means one lot of letters goes inside another.
'bananas' becomes 'mad' (slang for insane).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'mad' in reverse letter order is 'dam'.
'a'+'smith'='asmith'
'asmith' going around 'dam' is 'ADAM SMITH'.
(Other definitions for adam smith that I've seen before include "Economist" , "Advocate of free trade" , "The Wealth of Nations author" , "Moral philosopher" .)
'economist a forger' is the definition.
I can't judge whether this defines the answer.
'eating bananas up' is the wordplay.
'eating' becomes 'a' (I am not sure about this - if you are sure you should believe this answer much more).
'bananas' becomes 'mad' (slang for insane).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'mad' written backwards gives 'dam'.
'a'+'dam'='ADAM'
(Other definitions for adam that I've seen before include "Man No. 1" , "Man on the ceiling of the Sistine Chapel" , "First guy" , "one might confuse with total stranger" , "First Christian ancestor" .)