One's going to sea, so it's said — more easily with this? (3-6)

'said more easily with this?' is the definition.
The definition suggests a singular noun which matches the answer.

'one's going to sea so it's' is the wordplay.
I cannot really see how this works, but
'going' could be 'on' (both can mean functioning or activated) and 'on' is located in the answer.
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is found in the answer.
'one' could be 'i' (Roman numeral) and 'i' is found in the answer.
This explanation may well be incorrect...

Can you help me to learn more?