Mistake from British official ultimately in front of subordinate (7)
I believe the answer is:
blunder
'mistake' is the definition.
(I know that mistake can be written as blunder)
'british official ultimately in front of subordinate' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'ultimately' suggests the final letters.
'in front of' says to put letters next to each other.
'subordinate' becomes 'under' (similar in meaning).
The final letter of 'official' is 'l'.
'b'+'l'+'under'='BLUNDER'
'from' is the link.
(Other definitions for blunder that I've seen before include "Gross mistake" , "Stupid mistake" , "Clumsy mistake, gaffe" , "Embarrassing mistake" , "Clumsy error" .)