Hi lady bee.
re 72 - not sure about my answer yet for that one
78 Think 'golf' for peg and 2 letter word for work and anagram
Hope this helps.
Any help please for 84. Striking effect of chapter in contrary story (5) and 36. Pi ( Get to the root of this one!) (6)
Try googling 'striking effect' and although lots of headings just give meanings for striking, if you scroll down, you'll get to striking effect and should get your answer there.