Spy to admit one's easily influenced (6)
I believe the answer is:
pliant
'easily influenced' is the definition.
(I've seen this before)
'spy to admit one's' is the wordplay.
'spy' becomes 'plant' (someone planted somewhere to spy).
'to admit' indicates putting letters inside.
'one' becomes 'I' (Roman numeral).
'plant' going around 'i' is 'PLIANT'.
(Other definitions for pliant that I've seen before include "Flexible and easily manipulated" , "Not firm" , "Flexible, easy to bend" , "Bendable" , "docile" .)