Second attendant describes the hour around midnight when they were moving convulsively (9)

'moving convulsively' is the definition.
'twitching' can be an answer for 'moving' (twitching is a kind of moving). I'm unsure of the 'convulsively' bit.

'second attendant describes the hour around midnight when they' is the wordplay.
I cannot really see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
'hour' could be 'h' (abbreviation) and 'h' is found in the answer.
'around' could be 'c' (abbreviation for 'circa') and 'c' is present in the answer.
'midnight' could be 'g' (the middle letter in 'night') and 'g' is found in the answer.
'second attendant' could be 't' (2nd letter of 'attendant') and 't' is present in the answer.
This may be the basis of the clue (or it may be nonsense).

'were' is the link.

Can you help me to learn more?