Researched old quarry used in commercial (8)
I believe the answer is:
examined
'researched' is the definition.
The answer and definition can be both related to thinking as well as being past participle verbs.
Perhaps they are linked in a way I don't understand?
'old quarry used in commercial' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'quarry' becomes 'mine' (type of mine).
'used in' means one lot of letters goes inside another.
'commercial' becomes 'ad' (abbreviation for advertisement).
'mine' going within 'ad' is 'amined'.
'ex'+'amined'='EXAMINED'
Can you help me to learn more?
(Other definitions for examined that I've seen before include "Analysed, tested" , "Questioned closely" , "Observed and checked out" , "Looked into something closely" , "Closely inspected" .)