Drive one mile, exercise taken by learner (5)
I believe the answer is:
impel
'drive' is the definition.
(I know this)
'one mile exercise taken by learner' is the wordplay.
'one' becomes 'I' (Roman numeral).
'mile' becomes 'm' (common abbreviation).
'exercise' becomes 'pe' (Physical Education).
'taken by' is a charade indicator (letters next to each other).
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'i'+'m'+'pe'+'l'='IMPEL'
(Other definitions for impel that I've seen before include "Egg" , "Urge or propel" , "Make" , "Goad" , "Cause to move forward" .)