When uncle is in a state (5)
I believe the answer is:
assam
'a state' is the definition.
(I've seen this before)
'when uncle' is the wordplay.
'when' becomes 'as'.
'uncle' becomes 'sam' (Uncle Sam is an example).
'as'+'sam'='ASSAM'
'is in' acts as a link.
(Other definitions for assam that I've seen before include "Indian province" , "Top quality tea" , "North-east Indian tea state" , "place associated with tea" , "Indian tea-producing region" .)