Burning to join the marine band (7)
I believe the answer is:
searing
'burning' is the definition.
(thesaurus)
'join the marine band' is the wordplay.
'join' is a charade indicator (letters next to each other).
'the marine' becomes 'sea' (both can mean 'of the sea').
'band' becomes 'ring' (a ring is a band of metal).
'sea' next to 'ring' is 'SEARING'.
'to' is the link.
(Other definitions for searing that I've seen before include "Scorching" , "An aromatic liquid; aumbry (anag.)" .)