The other side open 1C even though you have a 5 card spade suit you only have 8 HCP AND you and partner are vulnerable, pass. Partner overcalls hearts (you have no support for them) and east bids 1NT. All pass.
Plan Before You Play
Your defensive plan: Lead out your top spades. If the opposition could have bid spades they would have, so maybe your side has the spade length. Do not lead fourth highest, this gives the other side winners with if they have JS and QS. Lead out KS and then AS and a low one. Hopefully your long diamonds will give you an entry later in the game to play your last two spade winners.
The Play
Watching your partners first discard on the diamonds you notice partner throw a heart play a heart, so just maybe they have club strength, switch to your to clubs which have not been played yet, partner can make another 2 tricks.
Comment
Counting the cards as you play you see that Declarer is out of spades after three rounds (so is partner) You need to switch to a side suit where partner may have some winners- either hearts or spades are good. I fyoiu and partner end up in 3S you go 1 light for -100 points
The above commentary is intended as a guideline only. As with any Bridge hand there are many ways to bid and play any hand.