Spotted outside hotel, using gloss (5)
I believe the answer is:
sheen
'gloss' is the definition.
(I've seen this before)
'spotted outside hotel' is the wordplay.
'spotted' becomes 'seen' (I've seen this in another clue).
'outside' means one lot of letters goes inside another (some letters go outside others).
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'seen' enclosing 'h' is 'SHEEN'.
'using' is the link.
(Other definitions for sheen that I've seen before include "brilliance" , "Surface shine" , "Soft lustre on a surface" , "Polish" , "actor?" .)