Rush back inside to evade eradication (4)
I believe the answer is:
reed
'rush' is the definition.
(I've seen this before)
'back inside to evade eradication' is the wordplay.
'back' says the letters should be written backwards.
'inside' indicates the answer is hidden within the clue.
'deer' can be found hidden inside 'evade eradication'.
'deer' backwards is 'REED'.
(Other definitions for reed that I've seen before include "'It vibrates in a clarinet, say (4)'" , "A blade of march grass" , "Marsh plant with tall straight stem" , "oboe part" , "Coarse grass in the organ pipe" .)