Many dogs missing summit (6)
I believe the answer is:
oodles
'many' is the definition.
(I've seen this before)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for oodles that I've seen before include "Loosed among lots" , "Large indefinite number" , "'Lashings, heaps (6)'" , "Plenty" , "masses" .)