Overtake one on desire (7)
I believe the answer is:
passion
'desire' is the definition.
(I know that passion is a type of desire)
'overtake one on' is the wordplay.
'overtake' becomes 'pass' (as in passing on a road).
'one' becomes 'I' (Roman numeral).
'pass'+'i'+'on'='PASSION'
(Other definitions for passion that I've seen before include "Great emotion" , "Strong feeling, or anger or desire possibly" , "Fervent love" , "Strong emotion, anger or love" , "fire" .)