Isomer of hydrocarbon? Trace one doctor? (8)
I believe the answer is:
carotene
'isomer of hydrocarbon?' is the definition.
'carotene' can be an answer for 'hydrocarbon?' (carotene is a kind of hydrocarbon). I am not sure about the 'isomer of' bit.
'trace one doctor?' is the wordplay.
'doctor?' indicates an anagram (I've seen 'doctor' mean this).
'trace'+'one'='traceone'
'traceone' anagrammed gives 'CAROTENE'.
Can you help me to learn more?
(Other definitions for carotene that I've seen before include "Orange plant pigment" , "plant hydrocarbon" , "Orange or red vegetable pigment, source of vitamin A" , "Coloured substance in carrots" , "Orange stuff" .)