Leading double-O M frets about (8)
I believe the answer is:
foremost
'leading' is the definition.
(foremost means leading or principal)
'double-o m frets about' is the wordplay.
I cannot quite understand how this works, but
'o' is within the answer.
'm' is present in the answer.
'about' could be 're' ('re' means regarding or about) and 're' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for foremost that I've seen before include "Pre-eminent" , "First in time, place or importance" , "Principal" , "top" , "premier" .)