A letter in red for Oliver, say (4)
I believe the answer is:
reed
'oliver say' is the definition.
Although both the answer and definition are singular nouns, I don't understand how they can define each other.
'a letter in red' is the wordplay.
'a letter' becomes 'e' ().
'in' indicates putting letters inside.
'e' going into 'red' is 'REED'.
'for' is the link.
Can you help me to learn more?
(Other definitions for reed that I've seen before include "Tall grass of wet areas" , "Instrument; tall grass" , "Marsh or water plant" , "Tall stiff marsh or water grass" , "Stalk" .)