Something delightful more than once in middle-class novels (3,5)
I believe the answer is:
aga sagas
'middle-class novels' is the definition.
(term for a novel about a middle-class family)
'something delightful more than once' is the wordplay.
'something delightful' becomes 'agas' (something delightful might be called 'a gas').
'more than once' indicates the doubling of some letters.
'agas' duplicated is 'AGA-SAGAS'.
'in' is the link.
(Other definitions for aga sagas that I've seen before include "popular British novels" , "Middle-class semi-rural novels" , "middle-class tales?" .)