Ring hotel salon endlessly (4)
I believe the answer is:
halo
'ring' is the definition.
(I've seen this before)
'hotel salon endlessly' is the wordplay.
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'endlessly' means to look at the middle letters (the ends of the words are removed).
The middle letters of 'salon' are 'alo'.
'h'+'alo'='HALO'
(Other definitions for halo that I've seen before include "Circle of light round the sun or moon" , "Symbol of sainthood" , "Ring of light (signifying holiness)" , "that could make one light-headed?" , "Luminous sign of saintliness" .)