Singles in hotel - time to be frank! (6)
I believe the answer is:
honest
'frank' is the definition.
('honest' can be similar in meaning to 'frank')
'singles in hotel time' is the wordplay.
'singles' becomes 'ones' ('one' can be a synonym of 'single').
'in' means one lot of letters goes inside another.
'hotel' becomes 'h' (phonetic alphabet: alpha, bravo, charlie etc.).
'time' becomes 't'.
'h'+'t'='ht'
'ones' going within 'ht' is 'HONEST'.
'to be' acts as a link.
(Other definitions for honest that I've seen before include "Law-abiding" , "Fair and free of deceit" , "See 1" , "Truthful and trustworthy" , "Upright and fair" .)