Crossword Genius

Inflexibly cunning, snaring seabird (7)

Ross

I believe the answer is:

sternly

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'inflexibly' is the definition.
Both the definition and answer are adverbs. Perhaps you can see a link between them that I can't see?

'cunning snaring seabird' is the wordplay.
'cunning' becomes 'sly' (synonyms).
'snaring' indicates putting letters inside.
'seabird' becomes 'tern' (tern is a kind of seabird).
'sly' enclosing 'tern' is 'STERNLY'.

Can you help me to learn more?

(Other definitions for sternly that I've seen before include "Cruelly" , "In serious way" .)

I've seen this clue in The Times.
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