What does the cryptic crossword clue "The marine in charge of heat (7)" mean?

The wordplay uses a charade (building blocks). THE (synonym="THE") + RM (synonym="RM") + IC (synonym="IC") = THERMIC The answer is THERMIC.

The marine in charge of heat (7)

Guardian Cryptic #25278 | 1 Down | 2011-03-24 flower