Couple without one fit story (7)
I believe the answer is:
parable
'story' is the definition.
(parable is a kind of story)
'couple without one fit' is the wordplay.
'couple' becomes 'pr'.
'without' indicates putting letters inside ('without' can be similar in meaning to 'outside').
'one' becomes 'a'.
'fit' becomes 'able' ('able' can be similar in meaning to 'fit'**).
'pr' placed around 'a' is 'par'.
'par'+'able'='PARABLE'
(Other definitions for parable that I've seen before include "Bible story" , "scripture lesson" , "Gospel story" , "Story illustrating moral lesson" , "Exemplum" .)