Operator rejects working in rush (5)
I believe the answer is:
surge
'rush' is the definition.
('surge' can be a synonym of 'rush')
'operator rejects working' is the wordplay.
'operator' becomes 'surgeon' (I've seen this before).
'rejects' indicates named letters should be taken away.
'working' becomes 'on'.
'surgeon' with 'on' taken out is 'SURGE'.
'in' is the link.
(Other definitions for surge that I've seen before include "Increase rapidly in intensity" , "Sudden flow" , "Move rapidly forward like a wave" , "Rapidly rising water" , "Sudden rapid rise" .)