Secret drinker comes to earth in Morecambe? (8)
'secret' is the definition.
(similar in meaning)
'drinker comes to earth in morecambe?' is the wordplay.
'drinker' becomes 'sot' (sot is a kind of drinker).
'comes to' is a charade indicator (letters next to each other).
'earth' becomes 'e'.
'in' is an insertion indicator.
'morecambe?' becomes 'eric' (I've seen this in other clues).
'sote' put inside 'eric' is 'ESOTERIC'.
(Other definitions for esoteric that I've seen before include "Other-worldly", "Understood by only a few people", "Occult", "Intelligible only to the initiated", "Mysterious to all but a chosen few".)