Bus lanes redesigned across east and south generating capability (10)

'capability' is the definition.
(capability can mean the ability to be useful)

'bus lanes redesigned across east and south' is the wordplay.
'redesigned' is an anagram indicator.
'across' indicates putting letters inside.
'east' becomes 'e' (abbreviation).
'and' says to put letters next to each other.
'south' becomes 's' (abbreviation).
'bus'+'lanes'='buslanes'
'buslanes' anagrammed gives 'usablens'.
'e'+'s'='es'
'usablens' going around 'es' is 'USABLENESS'.

'generating' is the link.