The food you have in your mouth (6)
I believe the answer is:
tongue
'mouth' is the definition.
(thesaurus)
'the food you have in your' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
'food' could be 'e' (E is an example) and 'e' is found in the answer.
'you' could be 'u' (commonly used in online communication) and 'u' is found within the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for tongue that I've seen before include "One gut in the mouth" , "Style of speaking; lick" , "dialect" , "rudely, one could be put out" , "spit" .)