Unhappy guests -- about 50 without bottle (7)
I believe the answer is:
gutless
'without bottle' is the definition.
('bottle' can be 'gut' (thesaurus) so maybe 'without bottle' can be ''gutless')
'unhappy guests about 50' is the wordplay.
'unhappy' is an anagram indicator.
'about' is an insertion indicator.
'50' becomes 'l' (Roman numeral).
'guests' with letters rearranged gives 'gutess'.
'gutess' placed around 'l' is 'GUTLESS'.
(Other definitions for gutless that I've seen before include "Cowardly, lacking intestines" , "Showing no evidence of bottle" , "Lacking courage and determination" , "Lacking any backbone" , "Chicken-livered" .)