There are elements in their make-up which will raise the temperature (8,5)

'will raise the temperature' is the definition.
I can't judge whether this defines the answer.

'there are elements in their make-up' is the wordplay.
I cannot really understand how this works, but
'elements' could be 'fires' (fire is a kind of element) and 'fires' is found in the answer.
'make' could be 'elect' (I've seen this before) and 'elect' is located in the answer.
The remaining letters 'ric' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).

'which' is the link.

Can you help me to learn more?