AJs in mid/late tounament

[Rizen]

Sorry, at work so I don't have the actual hand history handy:

Comments on ALL aspects of the play welcome.

This is a 20+2 Stars NL tournament, blinds are at 300/600 with a 50 ante and 9 players at the table. There are ~175 players left in the tournament with the top 63 getting paid. Getting just into the money on the bubble isn't as important to me as giving myself a reasonable chance at a final table finish. Rizen is dealt A [img]/images/graemlins/club.gif[/img]J [img]/images/graemlins/club.gif[/img] UTG and has ~6500 chips left. Table has been fairly tight often folding around to a standard raise of ~1800.

I (UTG) raise to 1800.
UTG+1 (player to my left, with a slightly deeper stack than mine around 7000 chips who has played pretty tight all game) cold calls for 1800, everyone else folds around leaving just me and the player to my left in with 4950 in the pot.

Flop comes A47 rainbow with the 4 being a club. I bet 2100 into the pot and the player to my left raises me all in after thinking about 10 seconds.

What do I do here?

Not only what do I do here, but what about my pre-flop line of an 1800 raise?

All comments welcome.

-Rizen