Eg shogun's promise to surround area on both sides (7)
I believe the answer is:
warlord
'eg shogun's' is the definition.
(the shoguns were Japanese warlords)
'promise to surround area on both sides' is the wordplay.
'promise' becomes 'word' (as in 'I give you my word').
'to surround' indicates putting letters inside.
'area' becomes 'a' (maths abbreviation).
'on' says to put letters next to each other.
'both sides' becomes 'rl' (I've seen this in other clues).
'a'+'rl'='arl'
'word' going around 'arl' is 'WARLORD'.
(Other definitions for warlord that I've seen before include "Regional military commander" , "Military leader" .)