Telly broadcast featuring old queen losing energy in persuasive speech (10)

'in persuasive speech' is the definition.
(showing eloquence)

'telly broadcast featuring old queen losing energy' is the wordplay.
'broadcast' is an anagram indicator (letters scattered or cast around).
'featuring' means one lot of letters goes inside another.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'losing' indicates named letters should be taken away.
'energy' becomes 'e' (physics symbol as in E=mc2).
'o'+'queen'='oqueen'
'oqueen' with 'e' removed is 'oquen'.
'telly' anagrammed gives 'eltly'.
'eltly' enclosing 'oquen' is 'ELOQUENTLY'.