London hotel: it's a cracker (4)
I believe the answer is:
ritz
'london hotel' is the definition.
'ritz' can be an answer for 'hotel' (I've seen this before). I'm unsure of the 'london' bit.
'it's a cracker' is the wordplay.
I cannot really see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
The remaining letters 'riz' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ritz that I've seen before include "Puttin' on the -- (song)" , "Luxurious hotel" , "Upmarket hotel" , "top hotel" , "Cesar --, Swiss hotelier" .)