What the Opposition does. (Yes, during recesses) (7)
I believe the answer is:
resists
'what the opposition' is the definition.
I can't tell whether this definition defines the answer.
'yes during recesses' is the wordplay.
'yes' becomes 'is' (I can't explain this - if you can you should believe this answer much more).
'during' means one lot of letters goes inside another.
'recesses' becomes 'rests' (I've seen this in another clue).
'is' put into 'rests' is 'RESISTS'.
'does' acts as a link.
Can you help me to learn more?
(Other definitions for resists that I've seen before include "Defies" , "Fights back" , "Struggles against" , "Is reluctant" , "Opposes, puts up fight" .)