Secret in family meant stopping short (11)
I believe the answer is:
clandestine
'secret' is the definition.
('clandestine' can be a synonym of 'secret')
'family meant stopping short' is the wordplay.
'family' becomes 'clan' (I've seen this before).
'meant' becomes 'destined'.
'stopping short' means to remove the last letter.
'destined' with its final letter removed is 'destine'.
'clan'+'destine'='CLANDESTINE'
'in' acts as a link.
(Other definitions for clandestine that I've seen before include "Undercover" , "Send a client (anag) - covert" , "through the backdoor" , "Secret" , "backroom" .)