Gilt ensign at sea, shimmering (10)

I believe the answer is:

glistening

'shimmering' is the definition.
(thesaurus)

'gilt ensign at sea' is the wordplay.
'at sea' indicates an anagram.
'gilt'+'ensign'='giltensign'
'giltensign' with letters rearranged gives 'GLISTENING'.

(Other definitions for glistening that I've seen before include "flashy" , "having a sparkle" .)

I've seen this clue in The Times.

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