First minerals excavation, in tin perhaps, is about to start (8)
I believe the answer is:
imminent
'about to start' is the definition.
I can't tell whether this definition defines the answer.
'first minerals excavation in tin perhaps' is the wordplay.
'first minerals' becomes 'm' (mst letter of 'minerals').
'excavation' becomes 'mine' (mine is a kind of excavation).
'in' is an insertion indicator.
'perhaps' is an anagram indicator.
'm'+'mine'='mmine'
'tin' anagrammed gives 'int'.
'mmine' going within 'int' is 'IMMINENT'.
'is' is the link.
Can you help me to learn more?
(Other definitions for imminent that I've seen before include "About to occur, any time now" , "About to happen very soon" , "Approaching fast" , "Likely to occur at any moment" , "Liable to occur soon" .)