Single-minded man? (8)
I believe the answer is:
bachelor
This could be a double definition.
'single' is the first definition.
(I've seen this before)
'minded man?' is the second definition.
'bachelor' can be an answer for 'man?' (bachelor is a kind of man). I am not certain of the 'minded' bit.
Can you help me to learn more?
(Other definitions for bachelor that I've seen before include "Non-married male" , "Unmarried man (with a degree?)" , "Single person" , "leading man at start of Wedding Cantata" , "Unmarried person" .)