Burst forth in another upturn (5)
I believe the answer is:
erupt
'burst forth' is the definition.
(I've seen this before)
'in another upturn' is the wordplay.
'in' indicates a hidden word.
'ERUPT' can be found hidden inside 'another upturn'.
(Other definitions for erupt that I've seen before include "Break forth" , "Break out like Etna" , "Discharge" , "Suddenly appear" , "Burst forth, like 25" .)