Set about English teams in Britain (9)
I believe the answer is:
beleaguer
'set' is the definition.
The answer and definition can be both related to competing as well as being verbs in their base form.
Perhaps there's a link between them I don't understand?
'english teams in britain' is the wordplay.
'english' becomes 'E' (abbreviation).
'teams' becomes 'league' (I can't justify this - if you can you should give a lot more credence to this answer).
'in' indicates putting letters inside.
'britain' becomes 'br' (abbreviation).
'e'+'league'='eleague'
'eleague' put inside 'br' is 'BELEAGUER'.
'about' acts as a link.
Can you help me to learn more?
(Other definitions for beleaguer that I've seen before include "Surround" , "Put in a very difficult position" , "put in a very difficult situation" .)