Series of uniform carbon copies seen in meeting (10)

'series' is the definition.
(succession is a kind of series)

'uniform carbon copies seen in meeting' is the wordplay.
'uniform' becomes 'u' (phonetic alphabet: alpha, bravo, charlie etc.).
'carbon copies' becomes 'cc' (common abbreviation in correspondence).
'seen in' means one lot of letters goes inside another.
'meeting' becomes 'session' (session is a kind of meeting**).
'u'+'cc'='ucc'
'ucc' put inside 'session' is 'SUCCESSION'.

'of' acts as a link.