A force retreats to a distance (4)
I believe the answer is:
afar
'distance' is the definition.
(I have seen 'great distance' mean 'afar' so perhaps 'distance' could also mean 'afar')
'a force retreats to a' is the wordplay.
'force' becomes 'f' (abbreviation in physics e.g. f=ma).
'retreats' becomes 'r' (this could be a standard abbreviation of which I'm unaware).
'to' says to put letters next to each other (I've seen this in other clues).
'r' after 'a' is 'ar'.
'a'+'f'+'ar'='AFAR'
Can you help me to learn more?
(Other definitions for afar that I've seen before include "Pull out at a distance" , "Way-out" , "beyond the horizon" , "quite some distance" , "Distant parts" .)