Secret tribe needs it badly (11)
I believe the answer is:
clandestine
'secret' is the definition.
(I know that secret can be written as clandestine)
'tribe needs it badly' is the wordplay.
'tribe' becomes 'clan' (synonyms).
'badly' indicates an anagram (letters in the wrong order).
'needs'+'it'='needsit'
'needsit' with letters rearranged gives 'destine'.
'clan'+'destine'='CLANDESTINE'
(Other definitions for clandestine that I've seen before include "Undercover" , "through the backdoor" , "Send a client (anag) - covert" , "Private" , "Concealed" .)