Im playing a low stakes cash game. Blinds are 0.25/0.50.
I have $20 at the table, BB has $18, seat 4 has $11.

Table folds round to seat 4 who calls the 0.25. I have As Ac and am in the SB. I raise to $0.75, the BB calls as does seat 4. Flop comes

4s Js 6s

I bet out with $1, BB folds, seat 4 raises to $3. At this stage I put him on either 10 J with 1 or 2 spades, K J again with a spade or possibly 2 or a middle pair with a spade. I call the raise. Turn comes

6d

I bet out $4, seat 4 goes all in for approx $7. I call, river comes

3h

he turns 10s 8s & wins pot.

Could /should I have been able to get away from this?

Raise more preflop. BTW, your preflop raise was illegal given the blinds, it should have to be at least to $1. You should've bumped it to at least $2.

Push allin after the flop raise if you're going to play. You have redraws if you're behind.

To answer your question, NO you shouldnt be getting away from this hand considering villian started the hand with less than a buyin. Your bet sizing however was not optinmal.

Raise a little more preflop. Bet out close to the pot on the flop and push if raised.

as most said..when he reraises you..push the flop...he wont have the made flush already and will be drawin and u have the nut draw...fairly standard play to push this