Pocketing ten quid, retired banker set forth (9)
I believe the answer is:
expounded
'set forth' is the definition.
(both can mean outlined or presented)
'pocketing ten quid retired banker' is the wordplay.
'pocketing' is an insertion indicator (I've seen this in other clues).
'ten' becomes 'x' (roman numeral).
'quid' becomes 'pound' (synonyms).
'retired' says the letters should be written backwards.
'banker' becomes 'dee' (I've seen this in other clues).
'dee' back-to-front is 'eed'.
'x'+'pound'='xpound'
'xpound' put within 'eed' is 'EXPOUNDED'.
(Other definitions for expounded that I've seen before include "made clear" , "Explained" , "commented on" .)