Crumpets cooked in range (8)
I believe the answer is:
spectrum
'range' is the definition.
(spectrum is a kind of range)
'crumpets cooked' is the wordplay.
'cooked' indicates anagramming the letters.
'crumpets' anagrammed gives 'SPECTRUM'.
'in' acts as a link.
(Other definitions for spectrum that I've seen before include "All the colours of 17 across" , "All the bands of colour seen in a rainbow" , "Complete colour range" , "'Broad range, scope (8)'" , "Range of colours, opinions etc" .)