Busy time in Saigon hotel she transformed (4,6)
I believe the answer is:
high season
'busy time' is the definition.
The definition suggests a singular noun which matches the answer.
'saigon hotel she transformed' is the wordplay.
I cannot really understand how this works, but
'hotel' could be 'h' (phonetic alphabet: alpha, bravo, charlie etc.) and 'h' is present in the answer.
an anagram of 'she' is 'hse' which is present in the answer.
an anagram of 'saigon' is 'igason' which is present in the remaining letters.
No letters remain.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Another definition for high season that I've seen is " peak tourist period".)