Welcoming people back, a single flower (7)
I believe the answer is:
anemone
'flower' is the definition.
(anemone is a kind of flower)
'welcoming people back a single' is the wordplay.
'welcoming' is an insertion indicator (I've seen this in other clues).
'people' becomes 'men' (man is a kind of person).
'back' shows that the letters should be reversed in order.
'single' becomes 'one' (I've seen this before).
'men' reversed gives 'nem'.
'a'+'one'='aone'
'nem' placed inside 'aone' is 'ANEMONE'.
(Other definitions for anemone that I've seen before include "bloomer" , "Plant; marine creature" , "Flower; marine polyp" , "perennial" , "Sea creature, also flower" .)