People initially inclined to be flexible (7)
I believe the answer is:
pliable
'flexible' is the definition.
(similar in meaning)
'people initially inclined' is the wordplay.
'people initially' becomes 'p' (I am not sure about this - if you are sure you should believe this answer much more).
'inclined' becomes 'liable' (I've seen this before).
'p'+'liable'='PLIABLE'
'to be' is the link.
(Other definitions for pliable that I've seen before include "Ductile" , "easily influenced" , "Easily bent" , "accommodating" , "Flexible" .)