Tan bairn's bottom after bit of bother and argument (5)
I believe the answer is:
brown
'tan' is the definition.
(I've seen this before)
'bairn's bottom after bit of bother and argument' is the wordplay.
'bottom' indicates one should take the final letters.
'after' is a charade indicator (letters next to each other).
'bit of' says to take the initial letters.
'and' says to put letters next to each other.
'argument' becomes 'row' (to row is to argue).
The last letter of 'bairn' is 'n'.
The first letter of 'bother' is 'b'.
'b'+'row'='brow'
'n' after 'brow' is 'BROWN'.
(Other definitions for brown that I've seen before include "Fry in a pan until it changes colour" , "Prime Minister, 2007-2010" , "Colour of toast" , "Kind of sweetener" , "Colour; ex-PM" .)