A range of crumpets (8)
I believe the answer is:
spectrum
'a range' is the definition.
(a spectrum is a range or variety)
'of crumpets' is the wordplay.
'of' indicates anagramming the letters (the answer comes from or 'of' the letters).
'crumpets' with letters rearranged gives 'SPECTRUM'.
(Other definitions for spectrum that I've seen before include "Broad range of related items" , "Array, range" , "Complete colour range" , "Light split by prism" , "Crumpets can provide the full array of colours" .)