The business lost first 500 ft through loss of courage (4,4)
I believe the answer is:
cold feet
'loss of courage' is the definition.
(I've seen this in another clue)
'the business lost first 500 ft' is the wordplay.
'the business' becomes 'co' (short for company).
'lost first' becomes 'l' (fst letter of 'lost').
'500' becomes 'D' (Roman numeral for 500).
'ft' becomes 'feet' (I can't explain this - if you can you should give a lot more credence to this answer).
'co'+'l'+'d'+'feet'='COLD FEET'
'through' acts as a link.
Can you help me to learn more?
(Other definitions for cold feet that I've seen before include "You'd have them if you were afraid to proceed" , "Loss of courage or confidence" , "Lack of courage or confidence" , "Fear or reluctance due to chilled extremities" , "Apprehensiveness" .)