One rowing over a vacuous rebellious bloke (7)
I believe the answer is:
oarsman
'one rowing' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'over a vacuous rebellious bloke' is the wordplay.
'over' is an insertion indicator.
'vacuous' suggests removing the centre.
'bloke' becomes 'oman' (I can't explain this - if you can you should believe this answer much more).
'rebellious' with its middle taken out is 'rs'.
'a'+'rs'='ars'
'ars' placed inside 'oman' is 'OARSMAN'.
Can you help me to learn more?
(Other definitions for oarsman that I've seen before include "One in a row" , "He rows" , "Member of rowing crew" , "Male rower" , "galley slave, say" .)