Ian's own (3)
I believe the answer is:
ain
'own' is the definition.
(synonyms)
'ian's' is the wordplay.
'ian' can be anagrammed to 'AIN'.
But, I'm not sure how this is indicated.
Can you help me to learn more?
(Other definitions for ain that I've seen before include "Own (Scot)" , "26 [ ]" , "Glaswegian personal" , "The Scot's own" , "Your own in Scottish dialect" .)