Bush, perhaps admitting Iran's first yielding (6)
I believe the answer is:
pliant
'yielding' is the definition.
(thesaurus)
'bush perhaps admitting iran's first' is the wordplay.
'bush perhaps' becomes 'plant' (bush is a kind of plant).
'admitting' is an insertion indicator.
'first' suggests taking the first letters.
The initial letter of 'irans' is 'i'.
'plant' placed around 'i' is 'PLIANT'.
(Other definitions for pliant that I've seen before include "Flexible, easy to bend" , "Supple or flexible" , "Able to move supply" , "Not firm" , "Accommodating" .)