Worried Iran to stay still (10)
I believe the answer is:
stationary
'still' is the definition.
(thesaurus)
'worried iran to stay' is the wordplay.
'worried' indicates an anagram.
'iran'+'to'+'stay'='irantostay'
'irantostay' is an anagram of 'STATIONARY'.
(Other definitions for stationary that I've seen before include "Parking" , "Unmoving" , "Fixed" , "Static" , "Not moving" .)