10d,unavoidable requirement,a?l???t?o?
11d,follow suit,i?i???e
17a,neat,t?i?
19a,plays the lead,s?a?s
20a,award,donation,????t
64a,solidly built and squat,??u?p?...
These two seem to have the same answer
42 Underground Skill - 9 ltrs
86 Going Underground - 9 ltrs
then there's 27 Don't let your marbles go 8 letters
all help greatly appreciated...