Do, when there’s a surprise development (5)
I believe the answer is:
twist
This clue could be a double definition.
'do' is the first definition.
(I've seen this before)
'a surprise development' is the second definition.
'twist' can be an answer for 'development' (twist is a kind of development). I am not sure about the 'a surprise' bit.
'when there's' acts as a link.
Can you help me to learn more?
(Other definitions for twist that I've seen before include "Strong thread" , "Turn into a distorted shape" , "Change of direction" , "Rotate rapidly" , "Wind round - distort" .)