Socialist move in sign of recession (3,5)
I believe the answer is:
red shift
'sign of recession' is the definition.
The definition suggests a singular noun which matches the answer.
'socialist move' is the wordplay.
'socialist' becomes 'red' (socialism is often associated with the colour red).
'move' becomes 'shift' (shifting is a kind of moving).
'red'+'shift'='RED SHIFT'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for red shift that I've seen before include "Receding-starlight phenomenon" , "evidence of recession?" , "Aspect of spectrum" , "Wavelength change of fast-moving objects" .)