Briton sensing change of tactics, initially (4)
I believe the answer is:
scot
'briton' is the definition.
(Scot is a type of Briton)
'sensing change of tactics initially' is the wordplay.
'initially' says to take the initial letters.
The first letters of 'sensing change of tactics' is 'SCOT'.
(Other definitions for scot that I've seen before include "levy, once" , "Jock?" , "Eg, Edinburgh native" , "Native of country of the UK" , "Glaswegian, say" .)