Algae scattered around Britain concern branch of mathematics (7)
I believe the answer is:
algebra
'branch of mathematics' is the definition.
(I've seen this in another clue)
'algae scattered around britain' is the wordplay.
'scattered' indicates anagramming the letters.
'around' indicates putting letters inside.
'britain' becomes 'br' (abbreviation).
'algae' with letters rearranged gives 'algea'.
'algea' going around 'br' is 'ALGEBRA'.
'concern' acts as a link.
I am not very happy about this link. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for algebra that I've seen before include "Numbers and letters branch of maths" , "Symbol-based branch of mathematics" , "Symbolic maths" , "Maths with letters representing numbers" , "Form of maths" .)