Code letter put in one's mouth (6)
I believe the answer is:
morsel
'in one's mouth' is the definition.
The definition suggests a singular noun which matches the answer.
'code letter' is the wordplay.
'code' becomes 'Morse' (Morse code).
'letter' becomes 'l' ().
'morse'+'l'='MORSEL'
'put' is the link.
Can you help me to learn more?
(Other definitions for morsel that I've seen before include "Crumb" , "a little food" , "(Tasty) bit" , "Small amount of food, a bite" , "Tiny piece" .)