Soft on guest's entertaining language (6)
I believe the answer is:
tongue
'language' is the definition.
(tongue is a kind of language)
'soft on guest's entertaining' is the wordplay.
'entertaining' indicates a hidden word.
'TONGUE' is hidden in the letters of 'soft on guests'.
(Other definitions for tongue that I've seen before include "They are hard to say" , "Part of body - language!" , "Ability to speak - a language" , "Speech" , "manner of speaking" .)