Figure skater's heart rate halved in Indonesia (7)
I believe the answer is:
sumatra
'in indonesia' is the definition.
('Sumatra' is part of 'indonesia')
'figure skater's heart rate halved' is the wordplay.
I cannot really understand how this works, but
'heart' could be 'sum' (synonyms) and 'sum' is found within the answer.
The remaining letters 'atra' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for sumatra that I've seen before include "Large Indonesian island" , "A US mart on an Indonesian island?" , "island in Indian ocean" , "Second largest Indonesian island" , "Eastern island" .)