Nothing in building complex has energy or colour (6,4)
I believe the answer is:
indigo blue
'nothing' is the definition.
I know nothing about this answer so I cannot tell whether it can be defined by this definition.
'in building complex has energy or colour' is the wordplay.
I cannot really see how this works, but
'in' is within the answer.
'energy' could be 'go' (I've seen this in other clues) and 'go' is found within the answer.
'colour' could be 'blue' (blue is a kind of colour) and 'blue' is located in the answer.
The remaining letters 'di' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for indigo blue that I've seen is " Deep colour - ie doubling (anag)".)