Add colour with new red coat and emerald top (8)
I believe the answer is:
decorate
'add colour' is the definition.
'decorate' can be an answer for 'add' (thesaurus). I'm not certain of the 'colour' bit.
'new red coat and emerald top' is the wordplay.
'new' is an anagram indicator.
'and' says to put letters next to each other.
'top' says to take the initial letters (in a down clue, the first letter is top).
The first letter of 'emerald' is 'e'.
'red'+'coat'='redcoat'
'redcoat' with letters rearranged gives 'decorat'.
'decorat'+'e'='DECORATE'
'with' is the link.
Can you help me to learn more?
(Other definitions for decorate that I've seen before include "Award a medal to" , "'Adorn, beautify (8)'" , "paint" , "Beautify by additions" , "Improve the look of" .)