Very merry (5)
I believe the answer is:
jolly
I believe this clue is a double definition.
'very' is the first definition.
(thesaurus)
'merry' is the second definition.
('jolly' can be a synonym of 'merry')
(Other definitions for jolly that I've seen before include "all-expenses-paid trip" , "Good-humoured, cheerful" , "Royal Marine (slang)" , "Very - jovial" , "Happy, cheerful" .)