Crush third bit of garlic, only crumbs left around it? (10)
I believe the answer is:
dishearten
'crush' is the definition.
'third bit of garlic only crumbs left around it?' is the wordplay.
I cannot quite see how this works, but
'bit' could be 'ear' (I have seen 'Bit of corn' mean 'ear' so perhaps 'bit' could also mean 'ear') and 'ear' is located in the answer.
'it?' could be 't' (abbreviation. e.g. in 'tis) and 't' is found in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for dishearten that I've seen before include "Take away bottle" , "dismay?" , "Cause (someone) to lose confidence" , "Take hope from" , "cast down" .)