Don't lead out. Check fold.
i disagree...if you raise preflop and then call a 1800 reraise you cant just hope to hit a set and fold everything else...
anyway.... let's see...after the preflop action there's about 7,5K in the pot...you bet 4K so , when the opponent moves all in he's got about 10K left, so it's 6K to call for you in a 21,5K pot...hard to fold more than 3,5 to 1...but what could he have?
a) total bluff : you are about a 70% favourite against 2 high cards if he's not on the flush draw...he reraised preflop so its very improbable he's got only 1 overcard
b) 2 high cards of clubs : you have a 45% chance to win the pot against 2 overcards of clubs...and with the action we've see AK , AQ of clubs are more than possible
c) higher pair : AA KK QQ JJ are probable here...and you only have about 12% chance against them...
d) under pair-connectors-A9-K9-A6-K6 are very unlikely given the action preflop...
now we have to give a) , b) and c) a %...
a) i give the bluff a 15% chance...may seem a bit high...but you see a lot of crazy and weird plays online...15% seems about right
b) the flush draw looks possible to me...but nothing more than a 25% chance
c) the higher pair looks to be the more likely hand he's got...60% seems right
so it is ( 15 * 0,7 + 25* 0,45 + 60* 0,12 ) = 0,29 or 29%
the odds were 3,5 to 1 , or 77% .. you have 29....29 +77 = 106 > 100 ( i know how to work with the odds but i cant explain very well

) ..so it should be a call, but a tough one in my opinion....this because you made a pretty large lead out bet IMO...i prefer to make a small feeler bet ( 2K or something )...the odds change a lot then
obviously if you have any info on your opponent you can change the percentages and decide if callin is a good or bad decision...
all this to say that i play 77 differently though lol

i use to fold 30% of the times, call 60% and raise 10%...and then decide my actions depending on the table, and my opponent...but i play the 77 UTG very weakly and conservative... i dont like that hand much in that position...