A mine boring copper, overdue to cave in (10)
I believe the answer is:
capitulate
'cave in' is the definition.
'capitulate' can be an answer for 'cave' (thesaurus). I'm not certain of the 'in' bit.
'a mine boring copper overdue' is the wordplay.
'mine' becomes 'pit' (down the pit).
'boring' means one lot of letters goes inside another (some letters must 'bore' a hole into other letters).
'copper' becomes 'cu' (chemical symbol).
'overdue' becomes 'late' (similar in meaning).
'a'+'pit'='apit'
'apit' put inside 'cu' is 'capitu'.
'capitu'+'late'='CAPITULATE'
'to' acts as a link.
Can you help me to learn more?
(Other definitions for capitulate that I've seen before include "Yield" , "Surrender" , "Give in" .)