Basically, the singer is saying that her love life is in shambles, and to cover it up she uses the metaphor of clowns. Years ago, in the circus, if someone fell off the trapeze or tightrope, they would hurriedly send in the clowns to cover up the mess and get everyone laughing again. There is a reference to this sort of tragedy in the first strophe: "me here at last on the ground/ you in mid-air." We can take from this that she has already fallen, and he is quickly falling behind her. So, to cover up this tragic love affair, "sending in the clowns" masks the despondency of the situation.
Basically, the singer is saying that her love life is in shambles, and to cover it up she uses the metaphor of clowns. Years ago, in the circus, if someone fell off the trapeze or tightrope, they would hurriedly send in the clowns to cover up the mess and get everyone laughing again. There is a reference to this sort of tragedy in the first strophe: "me here at last on the ground/ you in mid-air." We can take from this that she has already fallen, and he is quickly falling behind her. So, to cover up this tragic love affair, "sending in the clowns" masks the despondency of the situation.