Soon there's a vacancy and a girl is sent round (4)
I believe the answer is:
anon
'soon' is the definition.
(synonyms)
'a vacancy and a girl is sent round' is the wordplay.
I cannot really see how this works, but
'a' could be 'an' and 'an' is found within the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is located in the answer.
'round' could be 'o' (o is a circular letter) and 'o' is found in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'there's' is the link.
Can you help me to learn more?
(Other definitions for anon that I've seen before include "Of unknown identity, in short" , "Of unknown authorship" , "Immediately" , "Writer unknown" , "Presently - or unknown" .)