Cry over old Welsh chicken (6)
I believe the answer is:
yellow
'chicken' is the definition.
(as in cowardly)
'cry over old welsh' is the wordplay.
'cry' becomes 'yell' (synonyms).
'over' says to put letters next to each other (in a down clue, some letters go over others).
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'welsh' becomes 'W' (abbreviation).
'yell'+'o'+'w'='YELLOW'
(Other definitions for yellow that I've seen before include "Lily-livered" , "Colour of the fever flag" , "Sort of hammer, jersey or belly" , "Flaxen" , "Coldplay song; colour" .)