For the most part, work fast to get rich (7)
I believe the answer is:
opulent
'rich' is the definition.
(similar in meaning)
'for the most part work fast' is the wordplay.
'for the most part' means to remove the last letter.
'work' becomes 'opus' (I've seen this in another clue).
'fast' becomes 'lent' (Lent is a period of fasting in Christianity).
'opus' with its last letter taken off is 'opu'.
'opu'+'lent'='OPULENT'
'to get' is the link.
(Other definitions for opulent that I've seen before include "Wealthy, got lots of money" , "Well-to-dp. affluent" , "Luxurious or profuse" , "'Rich, luxurious (7)'" , "Rich, luxuriant" .)