Sherpa travelling with rest to high region (12)
I believe the answer is:
stratosphere
'high region' is the definition.
'stratosphere' can be an answer for 'region' (stratosphere is a kind of region). I'm not sure about the 'high' bit.
'sherpa travelling with rest to' is the wordplay.
'travelling with' indicates an anagram.
'rest'+'to'='restto'
'sherpa' with its letters mixed up with 'restto' gives 'STRATOSPHERE'.
Can you help me to learn more?
(Other definitions for stratosphere that I've seen before include "Layer of high air around the earth" , "Area containing ozone layer" , "Region about ten to fifty km above the earth" , "Layer above the earth where temperature generally increases with height" , "Zone high above earth" .)