Grand hotel bedroom regularly leaving one cold (6)
I believe the answer is:
heroic
'grand' is the definition.
(I know that grand can be written as heroic)
'hotel bedroom regularly leaving one cold' is the wordplay.
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'regularly leaving' indicates alternate letters (letters left out at regular intervals).
'one' becomes 'I' (Roman numeral).
'cold' becomes 'c' (eg on taps).
The alternate letters of 'bedroom' are 'ero'.
'h'+'ero'+'i'+'c'='HEROIC'
(Other definitions for heroic that I've seen before include "Epic" , "Very brave and noble" , "Showing no fear in the face of extreme difficulty" , "Gallant" , "Superhuman (efforts)" .)