In a tomb strangely harbouring one desire (8)
I believe the answer is:
ambition
'desire' is the definition.
(ambition is a kind of desire)
'in a tomb strangely harbouring one' is the wordplay.
'strangely' indicates an anagram.
'harbouring' is an insertion indicator.
'one' becomes 'i' (Roman numeral).
'in'+'a'+'tomb'='inatomb'
'inatomb' with letters rearranged gives 'ambiton'.
'ambiton' going around 'i' is 'AMBITION'.
(Other definitions for ambition that I've seen before include "Desire to get on" , "Drive to succeed" , "Urge to better oneself" , "Desire to achieve success" , "Objective" .)