Applies charge to honours? Liberal steps down (7)

'applies charge to' is the definition.
(to convert to an ion)

'honours? liberal steps down' is the wordplay.
'honours?' becomes 'lionises' (lionise can mean to worship or honour).
'liberal' becomes 'l' (abbreviation).
'steps down' suggests deleting specific letters (some letters leave or step down).
'lionises' with 'l' removed is 'IONISES'.