Rich old university acquiring power fast (7)
I believe the answer is:
opulent
'rich' is the definition.
(similar in meaning)
'old university acquiring power fast' is the wordplay.
'old' becomes 'o' (abbreviation).
'university' becomes 'U' (abbreviation as in UMass).
'acquiring' means one lot of letters goes inside another.
'power' becomes 'p' (symbol in physics).
'fast' becomes 'lent' (Lent is a period of fasting in Christianity).
'o'+'u'='ou'
'ou' enclosing 'p' is 'opu'.
'opu'+'lent'='OPULENT'
(Other definitions for opulent that I've seen before include "Well-to-dp. affluent" , "Wealthy, possessing riches" , "'Loaded'" , "Wealthy or lavish" , "Let up on, being wealthy" .)