Novel ally of solver and setter? (3,6,6)
I believe the answer is:
our mutual friend
'novel' is the definition.
(Charles Dickens novel)
'ally of solver and setter?' is the wordplay.
I cannot really see how this works, but
'ally' could be 'friend' (synonyms) and 'friend' is found in the answer.
'of' could be 'o' and 'o' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
(Other definitions for our mutual friend that I've seen before include "John Harmon" , "Novel" , "China we share" , "someone we both know" , "you and I know and like" .)