Tossing caber is about love for exercise (8)
I believe the answer is:
aerobics
'exercise' is the definition.
(aerobics is a kind of exercise)
'tossing caber is about love' is the wordplay.
'tossing' indicates an anagram.
'about' indicates putting letters inside.
'love' becomes 'o' (In tennis, 'love' means 'zero').
'caber'+'is'='caberis'
'caberis' with letters rearranged gives 'aerbics'.
'aerbics' going around 'o' is 'AEROBICS'.
'for' is the link.
(Other definitions for aerobics that I've seen before include "Exercise in the gym" , "Fitness system" , "Physical exercises" , "Sort of exercises that make Boris ache badly after an hour's gone" , "Forms of exercise" .)