I had left leading lady with little to do (5)
I believe the answer is:
idler
'with little to do' is the definition.
(someone with little to do)
'i had left leading lady' is the wordplay.
'i had' becomes 'I'd' (common contraction).
'left' becomes 'L' (common abbreviation).
'leading lady' becomes 'ER' (Elizabeth Regina).
'id'+'l'+'er'='IDLER'
(Other definitions for idler that I've seen before include "One reluctant to work" , "Layabout; ship crewman not on watch" , "Bummer" , "who makes no effort" , "papers" .)