Shortly, the doctors will escape the dust storm. That's extreme. (6)
I believe the answer is:
utmost
'extreme' is the definition.
(I know that extreme can be written as utmost)
'shortly the doctors will escape the dust storm' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is present in the answer.
'doctors' could be 'mos' (an MO is a Medical Officer) and 'mos' is located in the answer.
The remaining letters 'ut' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'that's' is the link.
Can you help me to learn more?
(Other definitions for utmost that I've seen before include "'Most extreme, greatest (6)'" , "Maximum effort" , "At furthest limit" , "Farthest" , "Furthest point or degree of effort" .)