Grab old boy to become overseas ruler (5)
I believe the answer is:
nabob
'overseas ruler' is the definition.
The answer and definition can be both people as well as being singular nouns.
Maybe there's a link between them I don't understand?
'grab old boy' is the wordplay.
'grab' becomes 'nab' (I've seen this before).
'old boy' becomes 'OB' (abbreviation for a private school 'old boy').
'nab'+'ob'='NABOB'
'to become' is the link.
Can you help me to learn more?
(Other definitions for nabob that I've seen before include "Person of conspicuous wealth or high status" , "Person of great wealth" , "One divining (water)" , "Wealthy influential person" , "he may be loaded" .)