Toy hens turn out to be best policy (7)
I believe the answer is:
honesty
'to be best policy' is the definition.
(I've seen this in another clue)
'toy hens turn' is the wordplay.
'turn' indicates an anagram.
'toy'+'hens'='toyhens'
'toyhens' is an anagram of 'HONESTY'.
'out' acts as a link.
(Other definitions for honesty that I've seen before include "Fairness" , "Plant; sincerity" , "that's easily cultivated" , "Probity; plant" , "A virtue" .)