Rum included in good diet (3)
I believe the answer is:
odd
'rum' is the definition.
(thesaurus)
'included in good diet' is the wordplay.
'included in' indicates a hidden word.
'ODD' is hidden in the letters of 'good diet'.
(Other definitions for odd that I've seen before include "Peculiar in uneven way" , "Number not divisible by two" , "Not matching" , "Peculiar or unpaired" , "Strange, peculiar" .)