Active males rest twice a year? (9)

I believe the answer is:

semestral

'twice a year?' is the definition.
(semestral means occurring every six months)

'active males rest' is the wordplay.
'active' indicates an anagram (the letters are active/moving).
'males'+'rest'='malesrest'
'malesrest' is an anagram of 'SEMESTRAL'.

I've seen this clue in The Guardian.

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