Swell: everyone included in blessing (7)
I believe the answer is:
balloon
'swell' is the definition.
(both can mean to expand or increase)
'everyone included in blessing' is the wordplay.
'everyone included' becomes 'all' (I've seen this in another clue).
'in' indicates putting letters inside.
'blessing' becomes 'boon' (synonyms).
'all' placed inside 'boon' is 'BALLOON'.
(Other definitions for balloon that I've seen before include "Inflatable sphere, may contain hot air" , "Inflatable thin rubber ball" , "Bag filled with gas or air" , "See 21" , "Inflatable - rapidly expand" .)