Related to heat that's somewhat tropical - or Icelandic? (7)
I believe the answer is:
Here is my best explanation:
'related to heat' is the definition.
I can't judge whether this defines the answer.
'somewhat tropical or icelandic?' is the wordplay.
'somewhat' indicates the answer is hidden within the clue.
'CALORIC' is hidden within 'tropical or icelandic'.
'that's' acts as a link.
(Another definition for caloric that I've seen is "Thermal".)