One day, looked at becoming rich (7)
I believe the answer is:
moneyed
'rich' is the definition.
('moneyed' can be similar in meaning to 'rich')
'one day looked at' is the wordplay.
'one day' becomes 'mon'.
'looked at' becomes 'eyed' (I've seen this before).
'mon'+'eyed'='MONEYED'
'becoming' acts as a link.
(Other definitions for moneyed that I've seen before include "Having means" , "Wealthy" , "Well-to-do" , "Rich" , "Well-heeled" .)