He entrances me, surviving at first in southern desert (9)

'he entrances' is the definition.
(someone who entrances or mesmerises people)

'me surviving at first in southern desert' is the wordplay.
'at first' suggests taking the first letters.
'in' means one lot of letters goes inside another.
'southern' becomes 's' (abbreviation).
'desert' becomes 'merit' (I've seen this before).
The initial letter of 'surviving' is 's'.
's'+'merit'='smerit'
's' placed inside 'smerit' is 'smerist'.
'me'+'smerist'='MESMERIST'