Some changeling is divine messenger (5)
I believe the answer is:
angel
'divine messenger' is the definition.
(I've seen this before)
'some changeling is' is the wordplay.
'some' indicates a hidden word (some of the parts of the word are used).
'ANGEL' can be found hidden inside 'changeling is'.
(Other definitions for angel that I've seen before include "lady (very kind)" , "Ministering spirit" , "Heavenly body" , "Messenger < is a nurse" , "One usually obliging" .)