One looks for mine to do well without time in company (10)
I believe the answer is:
prospector
'one looks for mine' is the definition.
'do well without time in company' is the wordplay.
'do well' becomes 'prosper' (I've seen this before).
'without' indicates putting letters inside ('without' can be similar in meaning to 'outside').
'time' becomes 't'.
'in' is an insertion indicator.
'company' becomes 'co' (abbreviation).
't' going into 'co' is 'cto'.
'prosper' going around 'cto' is 'PROSPECTOR'.
'to' acts as a link.
(Other definitions for prospector that I've seen before include "Gold-digger" , "Searcher after valuable ores" , "Searcher for minerals" , "One searching for valuable minerals" , "Clementine's father, perhaps?" .)