Solutions to JM Crossword 48

Across
1.  Back the law with a fifty and it will shelter you. (4)
Answer: WALL
Logic : "Back the law" is WAL; "fifty" is L. A WALL provides shelter.
3.  Discontinue breaking the pots ! (4)
Answer: STOP
Logic : STOP is an anagram of "pots" meaning "discontinue".
6.  A mixed range of emotions, may be a violent one. (5)
Answer: ANGER
Logic : Anagram of RANGE. It is a violent emotion.
8.  Run around the stadium in a flap. (3)
Answer: LAP
Logic : One round of the stadium is a LAP. It is contained in "fLAP". 
10. Negative tone but endlessly noisy. (3)
Answer: NOT
Logic : NOT is an anagram of "tone endlessly" i.e. "ton", meaning "negative"
12. In fact it is a performance. (3)
Answer: ACT
Logic : ACT is a "performance" contained in "fACT".
14. A scream in acrylic. (3)
Answer: CRY
Logic : CRY is a "scream" contained in "aCRYlic".
16. Following to the back of a ship with hesitation. (5)
Answer: AFTER
Logic : AFTER means "following". "the back of a ship" is AFT and "hesitation" is ER.
17. Mimics a distraught Paes ? (4) 
Answer: APES
Logic : APES is an anagram of "Paes" meaning "mimics"
18. A swain lost his ego to become a bird. (4)
Answer: SWAN
Logic : A "swain" without "I" is SWAn which is a bird.

Down
1.  "I am in good health, in fact pretty swell !" (4)
Answer: WELL
Logic : WELL means "in good health" it is contained in "swell".
2.  "Don't look so disgustingly pale! Jump ! (4)
Answer: LEAP
Logic : LEAP is an anagram of "pale" meaning "jump".
4.  Rent to the Royal Navy. (4)
Answer: TORN
Logic : TORN means "rent". "TO the Royal Navy" (RN) is TORN. 
5.  The role of a misplaced trap. (4)
Answer: PART
Logic : PART is an anagram of "trap" meaning "role".
7.  Large part of an ogre. At least a ton. (5)
Answer: GREAT
Logic : GREAT means "large". It is contained in "oGRE. AT".
9.  The car broke down at the curve. (3)
Answer: ARC
Logic : ARC is an anagram of "car" meaning "curve".
11. Rao exercised in a boat. (3)
Answer: OAR
Logic : OAR is an anagram of "Rao". It can be found "in a boat".
12. A place in a bare attic ? (4)
Answer: AREA
Logic : AREA means "a place". It is contained in "bARE Attic".
13. Grab that stumbling Kate ! (4)
Answer: TAKE
Logic : TAKE is an anagram of "Kate" meaning "grab".
14. A small credit partly owed to the flier. (4)
Answer: CROW
Logic : "A small credit" is CR. "partly owed" is OW. A CROW is a flier.
15. Move unsteadily towards north when sleepy. (4)
Answer: YAWN
Logic : "Move unsteadily" is YAW, "north" is N. We YAWN when sleepy.