Workers to return, joining a single plant (7)
I believe the answer is:
anemone
'plant' is the definition.
The answer is an example.
'workers to return joining a single' is the wordplay.
'workers' becomes 'men' (man is a kind of worker).
'to return' shows that the letters should be reversed in order.
'joining' means one lot of letters go next to another.
'single' becomes 'one' (I've seen this before).
'men' back-to-front is 'nem'.
'nem' put after 'a' is 'anem'.
'anem'+'one'='ANEMONE'
(Other definitions for anemone that I've seen before include "Plant; marine creature" , "Flower related to the buttercup" , "Plant with brightly coloured flowers - found also in sea" , "Plant; sea creature" , "A flower; mean one (anag.)" .)