All complainants initially taking oaths, right to drop charges (7)

'charges' is the definition.
('accuse' can be a synonym of 'charge')

'all complainants initially taking oaths right to drop' is the wordplay.
'initially' says to take the initial letters.
'taking' is an insertion indicator.
'right' says to take the final letters (the letter on the right of the word).
'to drop' becomes 'cues' (I can't justify this - if you can you should give a lot more credence to this answer).
The initial letters of 'all complainants' is 'ac'.
The last letter of 'oaths' is 's'.
's' going inside 'cues' is 'cuses'.
'ac'+'cuses'='ACCUSES'

Can you help me to learn more?