Tale suggesting it's normal to be fit (7)
I believe the answer is:
parable
'tale' is the definition.
(I know that parable is a type of tale)
'it's normal to be fit' is the wordplay.
'it's normal' becomes 'par' (as in par for the course).
'to be fit' becomes 'able' ('able' can be similar in meaning to 'fit').
'par'+'able'='PARABLE'
'suggesting' acts as a link.
(Other definitions for parable that I've seen before include "Gospel story" , "Sower, for one" , "Bible story" , "scripture lesson" , "Instructive story" .)