Batteries available with promotion in Riviera resort (10)

'batteries' is the definition.
The answer and definition can be both acts as well as being plural nouns.
Perhaps they are linked in a way I don't understand?

'available with promotion in riviera resort' is the wordplay.
'available' becomes 'on' (on can mean activated or available).
'with' means one lot of letters go next to another.
'promotion' becomes 'ad' (short for advert).
'in' means one lot of letters goes inside another.
'riviera resort' becomes 'cannes' (I've seen this in another clue).
'on'+'ad'='onad'
'onad' inserted into 'cannes' is 'CANNONADES'.

Can you help me to learn more?