Repeatedly carry out the termination of birds - now they're extinct (5)
I believe the answer is:
dodos
'they're extinct' is the definition.
The definition suggests an adverb but the answer is not. However, I know that 'extinct' relates to this answer.
'repeatedly carry out the termination of birds' is the wordplay.
'repeatedly' says to double the letters.
'carry out' becomes 'do' (synonyms).
'the termination of' says to take the final letters (the letter which terminates the word).
The final letter of 'birds' is 's'.
'do' doubled is 'dodo'.
'dodo'+'s'='DODOS'
'now' acts as a link.
Can you help me to learn more?
(Other definitions for dodos that I've seen before include "They never got up" , "they're no more" , "Extinct flightless birds" , "Extinct birds of Mauritius" .)