What may be evident in aura from star in colourful garment (3,5)
I believe the answer is:
red shift
'what may be evident in aura from star' is the definition.
(effect observed in light from distant stars)
'colourful garment' is the wordplay.
'colourful' becomes 'red' (similar in meaning).
'garment' becomes 'shift' (shift is a kind of garment).
'red'+'shift'='RED SHIFT'
'in' is the link.
(Other definitions for red shift that I've seen before include "Aspect of spectrum" , "Wavelength change of fast-moving objects" , "evidence of recession?" , "Receding-starlight phenomenon" .)