When unlikely to be welcomed into a hotel owned by us? (2,3,5)
I believe the answer is:
at all hours
'when' is the definition.
I know nothing about this answer so I can't tell whether this works.
'unlikely to be welcomed into a hotel owned by us?' is the wordplay.
'unlikely' becomes 'tall' (as in a tall tale).
'to be welcomed into' means one lot of letters goes inside another.
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'owned by us?' becomes 'ours' (something which is ours belongs to us).
'a'+'h'='ah'
'tall' going inside 'ah' is 'atallh'.
'atallh'+'ours'='AT ALL HOURS'
(Another definition for at all hours that I've seen is " At irregular times of day".)