Retired programmer keeps book (4)
I believe the answer is:
emma
'book' is the definition.
(Jane Austen novel)
'retired programmer keeps' is the wordplay.
'retired' is a reversal indicator.
'keeps' indicates the answer is hidden within the clue.
'amme' is hidden in the letters of 'programmer'.
'amme' in reverse letter order is 'EMMA'.
(Other definitions for emma that I've seen before include "classic work" , "Eponymous heroine" , "novelist's work" , "Jane Austen novel and Nelson's lover" , "companion for Nelson" .)