Concierge unusually with load of time describing earth-based system? (10)
I believe the answer is:
geocentric
'describing earth-based system?' is the definition.
'concierge unusually with load of time' is the wordplay.
'unusually' indicates anagramming the letters.
'with load of' means one lot of letters goes inside another ('load' can mean something being carried).
'time' becomes 't'.
'concierge' is an anagram of 'geocenric'.
'geocenric' placed around 't' is 'GEOCENTRIC'.
(Other definitions for geocentric that I've seen before include "Revolving around the earth" , "Having mundane perspective" .)