Lady is able to return calendar (7)
I believe the answer is:
almanac
'calendar' is the definition.
(thesaurus)
'lady is able to return' is the wordplay.
'lady' becomes 'alma' (**).
'is able to' becomes 'can' (I've seen this before).
'return' says the letters should be written in reverse.
'can' in reverse letter order is 'nac'.
'alma'+'nac'='ALMANAC'
(Other definitions for almanac that I've seen before include "Statistical calendar" , "Annual publication with mixed data, forecasts etc." , "periodic publication" , "Annual calendar of events" , "Calendar listing astronomical events etc" .)