ACROSS

 1  Everything is this, as kith and kin can prove. (8)

 5  and 30 A sign of fragility or a nickname as an associate of the humanitarian organization? (6,4,4)

10  I swam, leapfrogging to a religious man. (5)

11  A frightening sound by the old buggy could lead you to mine! (5,4)

12  I remember her show–about headgear–but it could make a Brahmin sage. (7)

13  God! Thunder leads to water in France–a pond he lived on! (7)

14  In Bristol, Ed overslept but made it in Ohio and Spain. (You can swear by it!) (6)

15  Done to a T, by the sound of it, and ran around a tee! (7)

18  Mrs. Spock, née Caputo, shows how to disable someone in the Sicilian manner. (7)

21  Five not paid up makes for swearing! (6)

24  This with Charlie is about trips to unwind in the return road. (7)

26  You’ll find a silver and agate display on the porch! (7)

27  You could say a snack eaten by the high-level commander is, but it would not be considered very specific. (2,7)

28  As around a contrasting coordinating conjunction, it really comes up against it! (5)

29  A famous climber, Madam Secretary has lost fifty! (6)

30  see 5

DOWN

 1  Carry on! Sure, Em! Crazy! Show this to the boss! (6)

 2  Reluctant to a portion–it’s revolting! (9)

 3  Sounds like this’ll be Ian’s symbol! Ouch! (7)

 4  That sassy kid has nothing but six on top, but it’s so shaky! (7)

 6  Polysaccharide that the little woman might find is gone? Pretty starchy! (7)

 7  Delve around right to the point of the slow, sad song. (5)

 8  Weight loss? Or the way one elucidates, sometimes longer than we’d like. (8)

 9  Tom, this makes it sound like an Englishman talking about love apples, but it’s just a saying. (6)

16  Write in–to the Soviet Union, to Louisiana–that they are almost surrounded by water! (9)

17  A little play on this is bad, and makes one quite nervous and flighty. (8)

19  If you can leer crookedly, it’s less dirty! (7)

20  It’s over, right? Your head knows it’s a treat! (6)

21  Six valid, if imperfect, seasons inspired him. (7)

22  If you are on it, you are not a Quaker–or a Shaker–and the awful wrath about Ma’s mate makes it worse. (7)

23  It’s normal, of course–look, it comes from the land of 10, 12 and 26. (6)

25  Give a leg up to an investor–it’s all in play! (5)