Old, major player in financial services circles (4)
I believe the answer is:
orbs
'circles' is the definition.
(I've seen this before)
'old major player in financial services' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'major player in financial services' becomes 'rbs' (I can't justify this - if you can you should believe this answer much more).
'o'+'rbs'='ORBS'
Can you help me to learn more?
(Other definitions for orbs that I've seen before include "sight" , "Ball shapes" , "They symbolise the power of kings" , "Lovely eyes, bros" , "Eyeballs" .)